C programming Interview questions and answers

C interview questions and answers for freshers. It is basic c language technical frequently asked interview questions and answers. It includes data structures, pointers interview questions and answers for experienced

Interview questions and answer of C with explanation for fresher

Write a c program to print Hello world without using any semicolon.

Answer

Explanation:

Solution: 1

void main(){

if(printf("Hello world")){

}

Solution: 2

void main(){

while(!printf("Hello world")){

}

Solution: 3

void main(){

switch(printf("Hello world")){

}

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Swap two variables without using third variable.

Answer

Explanation:

#include<stdio.h>

int main(){

int a=5,b=10;

//process one

a=b+a;

b=a-b;

a=a-b;

printf("a= %d b= %d",a,b);

//process two

a=5;

b=10;

a=a+b-(b=a);

printf("\na= %d b= %d",a,b);

//process three

a=5;

b=10;

a=a^b;

b=a^b;

a=b^a;

printf("\na= %d b= %d",a,b);

//process four

a=5;

b=10;

a=b-~a-1;

b=a+~b+1;

a=a+~b+1;

printf("\na= %d b= %d",a,b);

//process five

a=5,

b=10;

a=b+a,b=a-b,a=a-b;

printf("\na= %d b= %d",a,b);

return 0;

}

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What is dangling pointer in c?

Answer

Explanation:

Dangling pointer:

A dangling pointer arises when it continues to reference a memory address that once held a variable but has since been deallocated. This situation is commonly referred to as the dangling pointer problem.

Initially:

Later:

For example:

What will be output of following c program?

#include<stdio.h>

int *call();

int main(){

int *ptr;

ptr=call();

fflush(stdin);

printf("%d",*ptr);

return 0;

}

int * call(){

int x=25;

++x;

return &x;

}

Output: Garbage value

Note: Certain compilers may issue a warning message when returning the address of a local variable or a temporary.

Explanation: The variable 'x' is a local variable, confined to the scope and lifetime of the function call. Consequently, after returning the address of 'x', the variable 'x' becomes invalid, while the pointer 'ptr' persists in pointing to that location.

Solution of this problem:

Make the variable x is as static variable. In other word we can say a pointer whose pointing object has been deleted is called dangling pointer.

#include<stdio.h>

int *call();

int main(){

int *ptr;

ptr=call();

fflush(stdin);

printf("%d",*ptr);

return 0;

}

int * call(){

static int x=25;

++x;

return &x;

}

Output: 26

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What is wild pointer in c?

Answer

Explanation:

An uninitialized pointer in C is commonly referred to as a "wild pointer."

Example:

What will be output of following c program?

int main(){

int *ptr;

printf("%u\n",ptr);

printf("%d",*ptr);

return 0;

}

Output: Any address

Garbage value

In this context, 'ptr' is deemed a wild pointer due to its lack of initialization. It's crucial to distinguish between a NULL pointer and a wild pointer. A NULL pointer points to the base address of a segment, serving as a deliberate indication of no specific memory location, whereas a wild pointer lacks such a targeted assignment.

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What are merits and demerits of array in c?

Answer

Explanation:

Advantages:

(a) Facilitates straightforward access to each array element. (b) Reduces the need for an excessive number of variable declarations. (c) Ensures the storage of array elements in contiguous memory locations.

Drawbacks:

(a) Incurs memory wastage, and the array size cannot be altered dynamically during runtime. (b) Restricts the storage capability to a singular data type.

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Do you know memory representation of int a = 7 ?

Answer

Explanation:

Memory Representation:

For signed int a = 7; in Turbo C Compiler:

Binary equivalent of data 7 in 16 bits: 00000000 00000111 Data bits: 0000000 00000111 (Take the first 15 bits from the right side)

Sign bit: 0 (Take the leftmost one bit)

The first eight bits of the data bits from the right side, i.e., 00000111, will be stored in the leftmost byte from right to left side. The remaining seven bits of the data bits, i.e., 0000000, will be stored in the rightmost byte from right to left side.

For signed short int a = 7 in both Turbo C and Linux GCC Compiler:

Binary equivalent of data 7 in 16 bits: 00000000 00000111 Data bits: 0000000 00000111 (Take the first 15 bits from the right side)

Sign bit: 0 (Take the leftmost one bit)

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What is and why array in c?

Answer

Explanation:

An array in the C programming language is a composite data type capable of storing elements of the same data type in contiguous memory locations. These elements may include primitive types such as int, char, float, double, as well as more complex types like the address of a union, structure, pointer, function, or another array.

Example of array declaration:

int arr[5];

char arr[5];

float arr[5];

long double arr[5];

char * arr[5];

int (arr[])();

double ** arr[5];

Array is useful when:

(a) Arrays are particularly advantageous when dealing with a substantial volume of data of the same type. In scenarios where numerous variables of a similar kind are involved, it becomes cumbersome to individually name and manage each variable within a program. This challenge can be efficiently addressed by utilizing arrays. Instead of maintaining a lengthy list of variable names, an array provides a compact and organized way to store and process a large set of homogeneous data. This not only simplifies the code-writing process but also enhances program readability and maintainability.

For instance, consider the following scenario without using an array:

int ax=1, b=2, cg=5, dff=7, am=8, raja=0, rani=11, xxx=5, yyy=90, p, q, r, avg; avg = (ax + b + cg + dff + am + raja + rani + xxx + yyy + p + q + r) / 12; printf("%d", avg);

In contrast, the array-based approach significantly improves code conciseness:

int arr[] = {1, 2, 5, 7, 8, 0, 11, 5, 50}; int i, avg = 0; for (int i = 0; i < 12; i++) { avg += arr[i]; } printf("%d", avg / 12);

Utilizing arrays in this manner streamlines code, reduces the likelihood of errors, and enhances the overall efficiency of handling large datasets.

//PROCESS ONE

int main(){

int ax=1;

int b=2;

int cg=5;

int dff=7;

int am=8;

int raja=0;

int rani=11;

int xxx=5;

int yyy=90;

int p;

int q;

int r;

int avg;

avg=(ax+b+cg+dff+am+raja+rani+xxx+yyy+p+q+r)/12;

printf("%d",avg);

return 0;

}

If we will use array then above program can be written as:

//PROCESS TWO

int main(){

int arr[]={1,2,5,7,8,0,11,5,50};

int i,avg;

for(int i=0;i<12;i++){

avg=avg+arr[i];

}

printf("%d",avg/12);

return 0;

}

Question: Write a C program to find out average of 200 integer number using process one and two.

(b) Arrays offer a compelling solution when there is a need to store a considerable amount of data in a contiguous memory location. One of the key advantages of arrays is their inherent ability to ensure that elements are stored sequentially in memory. This contiguous allocation facilitates efficient access to elements through indexing, as memory locations are adjacent. This contrasts with non-array data structures where elements may be scattered in memory, leading to less predictable access patterns.

For instance, when dealing with a large dataset, the use of arrays ensures that the elements are stored consecutively, promoting efficient memory utilization and facilitating faster retrieval. This characteristic becomes especially beneficial when there is a requirement for sequential processing or when direct access to specific elements is crucial. In scenarios where data locality is essential for performance, arrays provide a straightforward and reliable mechanism for achieving continuous memory storage.

What will be output when you will execute the following program?

int main(){

int arr[]={0,10,20,30,40};

char *ptr=arr;

arr=arr+2;

printf("%d",*arr);

return 0;

}

Advantages of using arrays:

Conciseness and Easy Naming:

Arrays offer a concise way to represent a collection of elements under a single name. This simplifies the code and makes it easier to manage and remember the names of individual elements within the array.

Efficient Element Access:

The array name provides the base address of the array. Utilizing the increment operator, it becomes straightforward to sequentially visit each element of the array. This efficient access to elements is especially beneficial when performing operations or computations on the entire array.

Applications in Data Structures:

Arrays play a fundamental role in various data structures. Their ordered and contiguous nature makes them well-suited for implementations of essential data structures such as stacks, queues, and matrices. This versatility contributes to the effectiveness of arrays in organizing and manipulating data in different computational scenarios.

Array of Pointers in C:

An array of pointers in C is a composite data structure where each element of the array holds the address of another variable. This arrangement is particularly useful when dealing with multiple variables, and the array of pointers acts as a collection of references to these variables. Here's an example for better illustration:

int main(){

float a=0.0f,b=1.0f,c=2.0f;

float * arr[]={&a,&b,&c};

b=a+c;

printf("%f",arr[1]);

return 0;

}

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Why we use do-while loop in c? Also tell any properties which you know?

Answer

Explanation:

This loop, alternatively known as a post-tested loop, is employed when it is essential to ensure the execution of the loop at least once. The syntax is as follows:

do {

Loop body

} while (Expression);

Example:

int main(){

int num,i=0;

do{

printf("To enter press 1\n");

printf("To exit press 2");

scanf("%d",&num);

++i;

switch(num){

case 1:printf("You are welcome\n");break;

default : exit(0);

}

while(i<=10);

return 0;

}

Output: 3 3 4 4

If the loop body consists of only one statement, the use of braces becomes optional. For example:

(a)

int main(){

double i=5.5678;

printf("hi");

while(!i);

return 0;

}

Output: 3 3 4 4

(b)

int main(){

double i=5.63333;

printf("hi");

while(!i);

return 0;

}

Output: hi

(c)

int main(){

int x=25,y=1;

if(x>5)

printf(" ONE");

else if(x>10)

printf(" TWO");

else if(x==25)

printf(" THREE");

else

printf(" FOUR");

while(y--);

return 0;

}

Output: ONE ONE

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What is the meaning of prototype of a function?

Answer

Explanation:

Prototype of a function

The declaration of a function is referred to as the prototype of the function. The prototype encompasses the following information:

The return type of the function.
The parameters that the function accepts.

For instance, the prototype of the printf function is as follows:

int printf(const char *, …);

Namely, the return type of printf is of integer data type. Its first parameter is a constant character pointer, and the second parameter is specified as an ellipsis, indicating a variable number of arguments.

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Write a c program to modify the constant variable in c?

Answer

Explanation:

Constant variables can be modified through the use of pointers. For instance:

#include<stdio.h>

int main(){

int i=10;

int *ptr=&i;

*ptr=(int *)20;

printf("%d",i);

return 0;

}

Output: 20

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What is pointer to a function?

Answer

Explanation:

(1) What will be output if you will execute following code?

int * function();

int main(){

auto int *x;

int *(*ptr)();

ptr=&function;

x=(*ptr)();

printf("%d",*x);

}

int *function(){

static int a=10;

return &a;

}

Output: 10

Explanation: In this context, a 'function' refers to a function with a parameter of void data type and a return type of a pointer to int.

x=(*ptr)()

=> x=(*&functyion)() //ptr=&function

=> x=function() //From rule *&p=p

=> x=&a

So, *x = *&a = a =10

(2) What will be output if you will execute following code?

int find(char);

int(*function())(char);

int main(){

int x;

int(*ptr)(char);

ptr=function();

x=(*ptr)('A');

printf("%d",x);

return 0;

}

int find(char c){

return c;

}

int(*function())(char){

return find;

}

Output: 65

Explanation: In this scenario, the function named 'function' takes a parameter of void data type and returns another function. The returned function, in turn, accepts a parameter of char data type and has a return type of int.

x=(*ptr)(‘A’)

=> x= (*function ()) (‘A’) //ptr=function ()

//&find=function () i.e. return type of function ()

=> x= (* &find) (‘A’)

=> x= find (‘A’) //From rule*&p=p

=> x= 65

(3) What will be output if you will execute following code?

char * call(int *,float *);

int main(){

char *string;

int a=2;

float b=2.0l;

char *(*ptr)(int*,float *);

ptr=&call;

string=(*ptr)(&a,&b);

printf("%s",string);

return 0;

}

char *call(int *i,float *j){

static char *str="c-pointer.blogspot.com";

str=str+*i+(int)(*j);

return str;

}

Output: inter.blogspot.com

Explanation: The function named 'call' has a return type of a pointer to character. It takes two parameters: one is a pointer to int data type, and the other is a pointer to float data type. The pointer 'ptr' is declared to point to this function.

str= str+*i+ (int) (*j)

=”c-pointer.blogspot.com” + *&a+ (int) (*&b)

//i=&a, j=&b

=”c-pointer.blogspot.com” + a+ (int) (b)

=”c-pointer.blogspot.com” +2 + (int) (2.0)

=”c-pointer.blogspot.com” +4

=”inter.blogspot.com”

(4) What will be output if you will execute following code?

char far * display(char far*);

int main(){

char far* string="cquestionbank.blogspot.com";

char far *(*ptr)(char far *);

ptr=&display;

string=(*ptr)(string);

printf("%s",string);

}

char far *display(char far * str){

char far * temp=str;

temp=temp+13;

*temp='\0';

return str;

}

Output: cquestionbak

Explanation: The function 'display' is defined with a parameter of a pointer to character and a return type of a pointer to character. The pointer 'ptr' is assigned to point to this function.

temp is char pointer

temp=temp+13

temp=’\0’

In the given context, the two lines entail the replacement of the first dot character in the string variable 'cquestionbank\0blogspot.com' with a null character. It's worth noting that the '%s' format specifier is employed to print characters from the stream up to the null character in a string.

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Write a c program to find size of structure without using sizeof operator?

Answer

Explanation:

struct ABC{

int a;

float b;

char c;

};

int main(){

struct ABC *ptr=(struct ABC *)0;

ptr++;

printf("Size of structure is: %d",*ptr);

return 0;

}

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What is NULL pointer?

Answer

Explanation:

The literal meaning of a NULL pointer is a pointer that points to nothing, signifying the absence of a valid memory location. In practice, a NULL pointer typically points to the base address of a segment. Examples of NULL pointers include:

1. int *ptr=(char *)0;

2. float *ptr=(float *)0;

3. char *ptr=(char *)0;

4. double *ptr=(double *)0;

5. char *ptr=’\0’;

6. int *ptr=NULL;

What is meaning of NULL?

Answer:

NULL is a macro constant defined in header files such as stdio.h, alloc.h, mem.h, stddef.h, and stdlib.h. It is commonly employed to represent a null pointer, indicating that the pointer does not point to any valid memory location.

#define NULL 0

Examples:

(1)What will be output of following c program?

#include "stdio.h"

int main(){

if(!NULL)

printf("I know preprocessor");

else

printf("I don't know preprocessor");

}

Output: I know preprocessor

Explanation:

In logical terms, the expression !NULL = !0 = 1 asserts that the negation of a null condition or zero evaluates to true, represented by the value 1. In an 'if' condition, any non-zero number is considered true.

(2)What will be output of following c program?

#include "stdio.h"

int main(){

int i;

static int count;

for(i=NULL;i<=5;){

count++;

i+=2;

}

printf("%d",count);

}

Output: 3

(3)What will be output of following c program?

#include "stdio.h"

int main(){

#ifndef NULL

#define NULL 5

#endif

printf("%d",NULL+sizeof(NULL));

}

Output: 2

Explanation:

NULL + sizeof(NULL)

=0 + sizeoof(0)

=0+2 //size of int data type is two byte.

Copying is not permissible with a NULL pointer, as it denotes the absence of a valid memory location and attempting to copy data to or from it can lead to undefined behavior.

Example:

(4)What will be output of following c program?

#include "string.h"

int main(){

char *str=NULL;

strcpy(str,"c-pointer.blogspot.com");

printf("%s",str);

return 0;

}

Output: (null)

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What is difference between pass by value and pass by reference?

Answer

Explanation:

In C, parameters can be passed to a function using two distinct methods.

(a) Pass by value: In this approach, a copy of the actual variables is passed to the function as parameters. Consequently, any modifications made to these parameters within the function do not affect the original variables. For example:

#include<stdio.h>

int main(){

int a=5,b=10;

swap(a,b);

printf("%d %d",a,b);

return 0;

}

void swap(int a,int b){

int temp;

temp =a;

a=b;

b=temp;

}

Output: 5 10

(b) Pass by reference: In this approach, we pass the memory address of the actual variables to the function as parameters. Consequently, any modifications made to these parameters within the function directly impact the original variables. For example:

#incude<stdio.h>

int main(){

int a=5,b=10;

swap(&a,&b);

printf("%d %d",a,b);

return 0;

}

void swap(int *a,int *b){

int *temp;

*temp =*a;

*a=*b;

*b=*temp;

}

Output: 10 5

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What is size of void pointer?

Answer

Explanation:

The size of any type of pointer in C is independent of the data type it points to. Regardless of whether it's a char pointer, double pointer, function pointer, or null pointer, the size of all near pointers in C is two bytes. This rule extends to void pointers as well; their size is also two bytes.

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What is difference between uninitialized pointer and null pointer?

Answer

Explanation:

An uninitialized pointer is a pointer that points to an unknown memory location, whereas a null pointer is a pointer that points to a null value or the base address of a segment. For example:

int *p; //Uninitialized pointer

int *q= (int *)0; //Null pointer

#include<stdio.h>

int *r=NULL; //Null pointer

What will be output of following c program?

#include<string.h>

#include<stdio.h>

int main(){

char *p; //Uninitialized pointer

char *q=NULL; //Null pointer;

strcpy(p,"cquestionbank");

strcpy(q,"cquestionbank");

printf("%s %s",p,q);

return 0;

}

Output: cquestionbank (null)

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Can you read complex pointer declaration?

Answer

Explanation:

Rule 1: Assign priority to the pointer declaration by considering precedence and associativity according to the following table.

(): This operator functions as a bracket or function operator.

[]: This operator acts as the array subscription operator.

*: This operator functions as the pointer operator, distinct from its use as a multiplication operator.

Identifier: Although not classified as an operator, it represents the name of the pointer variable. Priority is consistently assigned to the name of the pointer.

Data type: Similarly not categorized as an operator, data types encompass modifiers (e.g., signed int, long double, etc.).

Understanding these concepts is better illustrated through examples:

(1) How to read following pointer?

char (* ptr)[3]

Answer:

Step 1: The operators () and [] share equal precedence. As per the rule of associativity (left to right), the first priority is assigned to ().

Step 2: Within the brackets, * and ptr have equal precedence. According to the right-to-left rule of associativity, the first priority is assigned to ptr, and the second priority goes to *.

Step 3: Assign the third priority to [].

Step 4: As the data type has the least priority, assign the fourth priority to char.

Now, read it in the following manner:

"ptr is a pointer to a one-dimensional array of size three, which contains char-type data."

(2) How to read following pointer?

float (* ptr)(int)

Answer:

Assign the priority by considering precedence and associativity.

Now, read it in the following manner:

'ptr is a pointer to a function whose parameter is of int type and return type is of float type.'

Rule 2: Assign the priority of each function parameter separately, and read each one separately. Understand it through the following example.

(3) How to read following pointer?

void (*ptr)(int (*)[2],int (*) void))

Answer:

Assign the priority considering the rule of precedence and associativity.

Now read it following manner:

ptr is pointer to such function which first parameter is pointer to one dimensional array of size two which contentint type data and second parameter is pointer to such function which parameter is void and return type is int data type and return type is void.

(4) How to read following pointer?

int ( * ( * ptr ) [ 5 ] ) ( )

Answer:

Assign the priority considering the rule of precedence and associativity.

Now read it in the following manner:

"ptr is a pointer to an array of size five, where the contents are pointers to functions with a parameter of void type and a return type of int."

(5) How to read following pointer?

double*(*(*ptr)(int))(double **,char c)

Answer:

Assign the priority considering the rule of precedence and associativity.

Now read it in the following manner:

ptr is a pointer to a function with a parameter of int type and a return type of a pointer to a function. The function it points to has the first parameter as a pointer to a pointer of double data type, the second parameter as a char type data, and the return type as a pointer to double data type.

(6) How to read following pointer?

unsigned **(*(*ptr)[8](char const *, ...)

Answer:

Assign the priority considering the rule of precedence and associativity.

Now read it in the following manner:

"ptr is a pointer to an array of size eight, where the contents of the array are pointers to functions. The functions have the first parameter as a pointer to a constant character, the second parameter as a variable number of arguments, and the return type as a pointer to a pointer of unsigned int data type."

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What are the parameter passing conventions in c?

Answer

Explanation:

1. Pascal: In this style, the function name (not necessarily) is in uppercase. Parameters in the function call are passed to the corresponding parameters in the function definition, maintaining the order.
2. Cdecl: In this style, the function name can be in both uppercase or lowercase. The first parameter of the function call is passed to the last parameter of the function definition. It is the default parameter passing convention.

Examples could be provided for each style to illustrate their usage.

1. What will be output of following program?

int main(){

static int a=25;

void cdecl conv1() ;

void pascal conv2();

conv1(a);

conv2(a);

return 0;;

}

void cdecl conv1(int a,int b)

{

printf("%d %d",a,b);

}

void pascal conv2(int a,int b)

{

printf("\n%d %d",a,b);

}

Output: 25 0
0 25

(2) What will be output of following program?

void cdecl fun1(int,int);

void pascal fun2(int,int);

int main(){

int a=5,b=5;

fun1(a,++a);

fun2(b,++b);

return 0;

}

void cdecl fun1(int p,int q){

printf("cdecl: %d %d \n",p,q);

}

void pascal fun2(int p,int q){

printf("pascal: %d %d",p,q);

}

Output:

cdecl: 6 6

pascal: 5 6

(3) What will be output of following program?

void cdecl fun1(int,int);

void pascal fun2(int,int);

int main(){

int a=5,b=5;

fun1(a,++a);

fun2(b,++b);

return 0;

}

void cdecl fun1(int p,int q){

printf("cdecl: %d %d \n",p,q);

}

void pascal fun2(int p,int q){

printf("pascal: %d %d",p,q);

}

Output:

cdecl: 6 6

pascal: 5 6

(4) What will be output of following program?

void convention(int,int,int);

int main(){

int a=5;

convention(a,++a,a++);

return 0;

}

void convention(int p,int q,int r){

printf("%d %d %d",p,q,r);

}

Output: 7 7 5

(5) What will be output of following program?

void pascal convention(int,int,int);

int main(){

int a=5;

convention(a,++a,a++);

return 0;}

void pascal convention(int p,int q,int r){

printf("%d %d %d",p,q,r);

}

Output: 5 6 6

(6) What will be output of following program?

void pascal convention(int,int);

int main(){

int a=1;

convention(a,++a);

return 0;

}

void pascal convention(int a,int b){

printf("%d %d",a,b);

}

Output: 1 2

(7) What will be output of following program?

void convention(int,int);

int main(){

int a=1;

convention(a,++a);

return 0;}

void convention(int a,int b){

printf("%d %d",a,b);

}

Output: 2 2

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What is the far pointer in c?

Answer

Explanation:

A far pointer is a type of pointer in a computer program that can access or point to the entire addressable memory of RAM. Specifically, it can access all 16 segments of the memory.

The size of a far pointer is 4 bytes or 32 bits. Examples:

(1) What will be output of following c program?

int main(){

int x=10;

int far *ptr;

ptr=&x;

printf("%d",sizeof ptr);

return 0;

}

Output: 4

(2)What will be output of following c program?

int main(){

int far *near*ptr;

printf("%d %d",sizeof(ptr) ,sizeof(*ptr));

return 0;

}

Output: 4 2

Explanation: ptr is a far pointer, whereas *ptr is a near pointer.

(3)What will be output of following c program?

int main(){

int far *p,far *q;

printf("%d %d",sizeof(p) ,sizeof(q));

}

Output: 4 4

The first 16 bits store the segment number, while the next 16 bits store the offset address.

Example:

int main(){

int x=100;

int far *ptr;

ptr=&x;

printf("%Fp",ptr);

return 0;

}

Output: 8FD8:FFF4

In the given context, '8FD8' represents the segment address, and 'FFF4' represents the offset address in hexadecimal number format.

Note: %Fp is used to print the offset and segment address of a pointer in the printf function in hexadecimal number format.

The header file 'dos.h' provides three macro functions for working with far pointers:

1.FP_OFF(): Used to obtain the offset address from a far address.
2.FP_SEG(): Used to obtain the segment address from a far address.
3.MK_FP(): Used to create a far address from segment and offset addresses.

Examples:

(1)What will be output of following c program?

#include "dos.h"

int main(){

int i=25;

int far*ptr=&i;

printf("%X %X",FP_SEG(ptr),FP_OFF(ptr));

}

Output: Any segment and offset address in hexadecimal number format respectively.

(2)What will be output of following c program?

#include "dos.h"

int main(){

int i=25;

int far*ptr=&i;

unsigned int s,o;

s=FP_SEG(ptr);

o=FP_OFF(ptr);

printf("%Fp",MK_FP(s,o));

return 0;

}

Output: 8FD9:FFF4 (Assume)

Note: The offset address, segment address, and far address of any far pointer are determined by the operating system and cannot be predicted.

Limitation of far pointer:

It is not possible to change or modify the segment address of a given far address by applying any arithmetic operation on it. In other words, using arithmetic operators, we cannot jump from one segment to another. If the far address is incremented beyond the maximum value of its offset address, instead of incrementing the segment address, it will repeat its offset address in a cyclic order.

Example:

(q)What will be output of following c program?

int main(){

int i;

char far *ptr=(char *)0xB800FFFA;

for(i=0;i<=10;i++){

printf("%Fp \n",ptr);

ptr++;

}

return 0;

}

Output:

B800:FFFA

B800:FFFB

B800:FFFC

B800:FFFD

B800:FFFE

B800:FFFF

B800:0000

B800:0001

B800:0002

B800:0003

B800:0004

This property of a far pointer, wherein it exhibits a cyclic nature within the same segment, is referred to as the cyclic nature of far pointers within the same segment.

Important points about far pointers:

Far pointers compare both offset address and segment address using relational operators

Examples:

(1)What will be output of following c program?

int main(){

int far *p=(int *)0X70230000;

int far *q=(int *)0XB0210000;

if(p==q)

printf("Both pointers are equal");

else

printf("Both pointers are not equal");

return 0;

}

Output: Both pointers are not equal

(2)What will be output of following c program?

int main(){

int far *p=(int *)0X70230000;

int far *q=(int *)0XB0210000;

int near *x,near*y;

x=(int near *)p;

y=(int near *)q;

if(x==y)

printf("Both pointer are equal");

else

printf("Both pointer are not equal");

return 0;

}

Output: Both pointers are equal

2. Far pointer doesn’t normalize.

Hide

What is a cyclic property of data type in c? Explain with any example.

Answer

Explanation:

#include<stdio.h>

int main(){

signed char c1=130;

signed char c2=-130;

printf("%d %d",c1,c2);

return 0;

}

Output: -126 126 (why?)

This situation is known as overflow of a signed char. The range of an unsigned char is -128 to 127. If a value greater than 127 is assigned, the variable's value will wrap around to a new value by moving in the clockwise direction, as depicted in the figure according to the number line. Similarly, assigning a number less than -128 requires moving in the anti-clockwise direction.

Hide

Pointers Interview questions
Data types Interview questions
Advance interview questions
String interview questions and answers
Commonly asked questions
TCS placement question

Pointers to pointers in c programming language

2013-03-03T22:47:00.000+05:30

C pointers to pointers: A pointer is pointing to another pointers is called pointers to pointer.

Examples of pointers to pointers in c:

What output can be expected upon executing the following code?

#include<stdio.h>

int main(){

int s=2,*r=&s,**q=&r,***p=&q;

printf("%d",p[0][0][0]);

return 0;

}

Output: 2

Explanation:

As we know p[i] =*(p+i)

So,

P[0][0][0]=*(p[0][0]+0)=**p[0]=***p

Another rule is: *&i=i

So,

***p=*** (&q) =**q=** (&r) =*r=*(&s) =s=2

Debugging questions in c with answers

2012-05-27T16:23:00.004+05:30

C debugging interview questions

C debugging questions with answers

1. Create a C program to initiate the shutdown of a Windows operating system using Turbo C. Save the following code in a file named 'close.c':

void main(void)
{
system("shutdown -s");
}

After saving the file, compile and execute the program in Turbo C. Close the Turbo C compiler and navigate to the directory where you saved 'close.c' (default directory: 'c:\tc\bin'). Double-click the executable file ('close.exe'). After a short delay, your Windows system will initiate a shutdown.

2. Compose a scanf statement capable of capturing an entire line of text, including spaces.

Answer:

void main() {

char a[30];

clrscr();

scanf("%[^\n]",a);

printf("%s",a);

getch();

}

3. Given the string "MATCHMAKING", write a program to read the string from the terminal and display the same in the following formats:

(a) MATCH MAKING
(b) MATCH
MAKING
(c) M.M.

4. I need it to write a C/C++ program that connects to a MySQL server and displays the global TIMEZONE.

Answer:

I can provide you with a simple example in C++ using the MySQL Connector/C++ library. Please note that you need to have the MySQL Connector/C++ installed and linked properly with your project.

Here's a basic example:

#include <mysql_driver.h> #include <mysql_connection.h> int main() { sql::mysql::MySQL_Driver *driver; sql::Connection *con; try { driver = sql::mysql::get_mysql_driver_instance(); con = driver->connect("tcp://127.0.0.1:3306", "your_username", "your_password"); // Connect to the MySQL server con->setSchema("information_schema"); // Execute a query to get the global timezone sql::Statement *stmt = con->createStatement(); sql::ResultSet *res = stmt->executeQuery("SELECT @@global.time_zone AS time_zone"); // Display the result while (res->next()) { std::cout << "Global Timezone: " << res->getString("time_zone") << std::endl; } delete res; delete stmt; delete con; } catch (sql::SQLException &e) { std::cerr << "# ERR: SQLException in " << __FILE__; std::cerr << "(" << __FUNCTION__ << ") on line " << __LINE__ << std::endl; std::cerr << "# ERR: " << e.what(); std::cerr << " (MySQL error code: " << e.getErrorCode(); std::cerr << ", SQLState: " << e.getSQLState() << " )" << std::endl; } return 0; }

Make sure to replace "tcp://127.0.0.1:3306", "your_username", and "your_password" with your MySQL server details.
Remember to include the necessary MySQL Connector/C++ headers and link against the library when compiling. The actual connection details (server address, username, and password) will depend on your MySQL setup.

5. A string (example "I am writing an email") is entered through the keyboard, write a program in C to get its reverse in a column as output i.e.:

writing

Answer:

void main()

{

char str[20];

char *ptr=str,*temp;

int i=0,j;

clrscr();

scanf("%[^\n]",str);

while(*ptr){

i++;

ptr++;

}

for(j=0;j

if(*ptr==' ')

{

temp=ptr;ptr--;temp++;

while((*temp!=' ')&&(*temp!='\0')) {

printf("%c",*temp);

temp++;

}

printf("\n");

}

else

{

ptr--;

}

while(*ptr!=' ') {

printf("%c",*ptr);

ptr++;

}

getch();

}

6. I want a C program to check whether a string is a palindrome or not where the string to be checked is passed as command line argument during execution.

Answer:

#include<string.h>

void main(int counter,char**string)

{

char *rev;

char str[15];

int i,j;

clrscr();

strcpy(str,string[1]);

printf("%s",str);

for(i=strlen(str)-1,j=0;i>=0;i--,j++)

rev[j]=str[i];

rev[j]='\0';

if(strcmp(rev,str))

printf("\nThe string is not a palindrome");

else

printf("\nThe string is a palindrome");

getch();

}

7. How to write a c program to display the source code of the program.

Answer:

If source code is available

#include<stdio.h>

void main()

{

char str[70];

FILE *p;

clrscr();

if((p=fopen("mod.c","r"))==NULL)

{

printf("\nUnable t open file string.txt");

exit(1);

}

while(fgets(str,70,p)!=NULL)

puts(str);

fclose(p);

getch();

}

8. Swapping of two number without using third variable

Answer:

void main()

{

int a=5,b=10;

clrscr();

//process one

a=b+a;

b=a-b;

a=a-b;

printf("a= %d b= %d",a,b);

//process two

a=5;b=10;

a=a+b-(b=a);

printf("\na= %d b= %d",a,b);

//process three

a=5;b=10;

a=a^b;

b=a^b;

a=b^a;

printf("\na= %d b= %d",a,b);

//process four

a=5;b=10;

a=b-~a-1;

b=a+~b+1;

a=a+~b+1;

printf("\na= %d b= %d",a,b);

//process five

a=5,b=10;

a=b+a,b=a-b,a=a-b;

printf("\na= %d b= %d",a,b);

getch();

}

9. How to convert decimal to binary in c program?

Answer

void main()

{

long int m,no=0,a=1;

int n,rem;

clrscr();

printf("Enter any decimal number->");

scanf("%d",&n);

m=n;

while(n!=0)

{

rem=n%2;

no=no+rem*a;

n=n/2;

a=a*10;

}

printf("The value %ld in binary is->",m);

printf("%ld",no);

getch();

}

10. Write a program to accept character and integer n from user and display next n character

Answer:

void main()

{

char c;

int n,i;

clrscr();

printf("insert one character and integer : ");

scanf("%c%d",&c,&n);

for(i=c+1;i<=c+n;i++)

printf("%c ",i);

getch();

}

Output:

insert one character and integer : c 4

d e f g

C debugging questions

Debugging questions in c

Aptitude questions and answers in c

2012-05-27T14:39:00.001+05:30

C programming aptitude questions and answers

Aptitude questions in interview

Total question: 32

Time: 60 minute

Total marks: 64

1. Find out the error if any, in the program.

#include<stdio.h>

int main(){

int i=1;

switch(i){

case 1: printf("\radioactive cats have 18 half-lives");

break;

case 1*2+4: printf("\bottle for rent -inquire within");

break;

}

return 0;

}

2. Find out the error, if any, in the following program.

#include<stdio.h>

int main(){

int a=10,b;

a= 5 ? b=100 : b=200;

printf("\n%d",b);

return 0;

}

3. In the following code, in which order the functions would be called?

a= f1(23,14)*f2(12/4)+f3();

a) f1, f2, f3

b) f3, f2, f1

c) The order may vary from compiler to compiler

d) None of the above

4. What would be the output of the following program?

#include<stdio.h>

int main(){

int i=4;

switch(i){

default:

printf("\n A mouse is an elephant built by the Japanese");

case 1:

printf(" Breeding rabbits is a hair raising experience");

break;

case 2:

printf("\n Friction is a drag");

break;

case 3:

printf("\n If practice make perfect, then no body's perfect");

}

return 0;

}

a) A mouse is an elephant built by the Japanese

b) Breeding rabbits is a hare raising experience

c) All of the above

d) None of the above

5. What is the output of the following program?

#include<stdio.h>

#define SQR(x) (x*x)

int main(){

int a,b=3;

a= SQR(b+2);

printf("%d",a);

return 0;

}

a) 25

b) 11

c) error

d) garbage value

6. In which line of the following, an error would be reported?

#include<stdio.h>

1. #define CIRCUM(R) (3.14*R*R);

2. int main()

3. {

4. float r=1.0,c;

5. c= CIRCUM(r);

6. printf("\n%f",c);

7. if(CIRCUM(r))==6.28)

8. printf("\nGobbledygook");

9. return 0;

10. }

a) line 1

b) line 5

c) line 6

d)line 7

7. What is the type of the variable b in the following declaration?

#define FLOATPTR float*

FLOATPTR a,b;

a) float

b) float pointer

c) int

d) int pointer

8. In the following code:

#include"stdio.h";

int main(){

FILE *fp;

fp= fopen("trial","r");

}

fp points to:

a) The first character in the file.

b) A structure which contains a "char" pointer which points to the first character in the file.

c) The name of the file.

d) None of the above.

9. We should not read after a write to a file without an intervening call to fflush(), fseek() or rewind() "TRUE/FALSE" ?

10. If the program (myprog) is run from the command line as myprog 1 2 3 , What would be the output?

#include<stdio.h>

int main(int argc, char *argv[]){

int i;

for(i=0;i<argc;i++)

printf("%s",argv[i]);

return 0;

}

a) 1 2 3

b) C:\MYPROG.EXE 1 2 3

c) MYP

d) None of the above

11. If the following program (myprog) is run from the command line as myprog 1 2 3, what would be the output?

#include<stdio.h>

int main(int argc, char *argv[]){

int i,j=0;

for(i=0;i<argc;i++)

j=j+ atoi(argv[i]);

printf("%d",j);

return 0;

}

a) 1 2 3

b) 6

c) error

d) "123"

12. If the following program (myprog) is run from the command line as :

myprog monday tuesday wednesday thursday

What would be the output?

#include<stdio.h>

int main(int argc, char *argv[]){

while(--argc <0)

printf("%s",*++argv);

return 0;

}

a) myprog monday tuesday wednesday thursday

b) monday tuesday wednesday thursday

c) myprog tuesday thursday

d) None of the above

13. In the following code, is p2 an integer or an integer pointer?

typedef int* ptr

ptr p1,p2;

14. Point out the error in the following program

#include<stdio.h>

int main(){

const int x;

x=128;

printf("%d",x);

return 0;

}

15. What would be the output of the following program?

#include<stdio.h>

int main(){

int y=128;

const int x=y;

printf("%d",x);

return 0;

}

a) 128

b) Garbage value

c) Error

d) 0

16. What is the difference between the following declarations?

const char *s;

char const *s;

17. What is the difference between the following declarations?

const char *const s;

char const *const s;

18. What would be the output of the following program?

#include<stdio.h>

int main(){

char near * near *ptr1;

char near * far *ptr2;

char near * huge *ptr3;

printf("%d %d %d",sizeof(ptr1),sizeof(ptr2),sizeof(ptr3));

return 0;

}

a) 1 1 1

b) 1 2 4

c) 2 4 4

d) 4 4 4

19. If the following program (myprog) is run from the command line as:

myprog friday tuesday Sunday

What would be the output?

#include<stdio.h>

int main(int argc, char*argv[]){

printf("%c",**++argv);

return 0;

}

a) m

b) f

c) myprog

d) friday

20. If the following program (myprog) is run from the command line as:

myprog friday tuesday sunday

What would be the output?

#include<stdio.h>

int main(int argc, char *argv[]){

printf("%c",*++argv[1]);

return 0;

}

a) r

b) f

c) m

d) y

21. If the following program (myprog) is run from the command line as:

myprog friday tuesday sunday

What would be the output?

#include<stdio.h>

int main(int argc, char *argv[]){

while(sizeof argv)

printf("%s",argv[--sizeof argv]);

return 0;

}

a) myprog friday tuesday sunday

b) myprog friday tuesday

c) sunday tuesday friday myprog

d) sunday tuesday friday

22. Find out the error in the following program.

#include<stdio.h>

int main(){

int a=10;

void f();

a=f();

printf("\n%d",a);

return 0;

}

void f(){

printf("\nHi");

}

23. In the following program how would you print 50 using p?

#include<stdio.h>

int main(){

int a[]={10, 20, 30, 40, 50};

char *p;

p= (char*) a;

}

24. Would the following program compile?

#include<stdio.h>

int main(){

int a=10,*j;

void *k;

j=k=&a;

j++;

k++;

printf("\n%u%u",j,k);

}

a) Yes

b) No, the format is incorrect

c) No, the arithmetic operation is not permitted on void pointers

d) No, the arithmetic operation is not permitted on pointers

25. According to ANSI specifications which is the correct way of declaring main() when it receives command line arguments?

a) main(int argc, char *argv[])

main(argc,argv)

int argc;

char *argv[];

main(){

int argc; char *argv[];

}

d) None of the above

26. What error would the following function give on compilation?

f(int a, int b){

int a;

a=20;

return a;

}

a) Missing parenthesis in the return statement

b) The function should be declared as int f(int a, int )

c) Re declaration of a

d) None of the above

27. Find out the error in the following program.

#include<stdio.h>

int main(){

const char *fun();

*fun()='A';

return 0;

}

const char *fun(){

return "Hello";

}

28. What would be the output of the following program?

#include<stdio.h>

int main(){

const int x=5;

int *ptrx;

ptrx=&x;

*ptrx=10;

printf("%d",x);

return 0;

}

a) 5

b) 10

c) Error

d) Garbage value

29. A switch statement cannot include

a) Constants as arguments

b) Constant expression as arguments

c) String as an argument

d) None of the above

30. How long the following program will run?

#include<stdio.h>

int main(){

printf("\nSonata Software");

main();

return 0;

}

a) Infinite loop

b) Until the stack overflows

c) All of the above

d) None of the above

31. On combining the following statements, you will get

char*p;

p=malloc(100);

a) char *p= malloc(100)

b) p= (char*)malloc(100)

c) All of the above

d) None of the above

32. What is the output of the following program?

#include<stdio.h>

int main(){

int n=5;

printf("\nn=%*d",n,n);

return 0;

}

a) n=5

b) n=5

c) n= 5

d) Error

Solution:

1. No error. Constant expression like 1*2+4 is acceptable in cases of a switch.

2. Lvalue required in function main(). The second assignment should be written in parenthesis as follows:

a= 5 ? b = 100 : (b=200);

3. c) The order may vary from compiler to compiler

4. c) All of the above

5. b) 11

6. d)line 7

7. a) float

8. b) A structure which contains a "char" pointer which points to the first character in the file.

9. True

10. b) C:\MYPROG.EXE 1 2 3

11. b) 6

12. b) monday tuesday wednesday Thursday

13. Integer pointer

14. x should have been initialized where it is declared.

15. a) 128

16. No difference

17. No difference

18. c) 2 4 4

19. b) f

20. b) f

21. c) sunday tuesday friday myprog

22. The program is trying to collect the value of a "void" function into an integer variable.

23. printf("\n%d",*((int*)p+4));

24. c) No, the arithmetic operation is not permitted on void pointers

25. a) main(int argc, char *argv[])

26. c) Re declaration of a

27. fun() returns to a "const char" pointer which cannot be modified

28. b) 10

29. c) string as an argument

30. b) Until the stack overflows

31. a) char *p= malloc(100)

32. c) n= 5

Aptitude questions for c

C basic questions

2012-05-27T14:20:00.003+05:30

C basic interview questions and answers for freshers

(1)

void main(){

char i;

clrscr();

for(i=120;i<=128;i++){

printf("%d ",i);

}

getch();

}

Output: Infinite loop

(2)

void main(){

int i;

clrscr();

for(i=0,i++,i<=5;i++,i<=2;i=0,i<=5,i+=3){

printf("%d ",i);

}

getch();

}

Output: 2

(3)

void main(){

int i=1;

clrscr();

for(;;){

printf("%d ",i);

}

getch();

}

Output: Infinite loop

(4)

void main(){

int i=2;

clrscr();

for(i=0;i<=3;i++){

static int i;

i=i+8;

}

printf("%d",i);

getch();

}

Output: 4

(5)

extern int j;

void main(){

int i=0;

clrscr();

for(i=0;i<=2;i+=1){

int j=5;

printf("%d ",j);

j++;

}

getch();

}

int j=25;

Output: 5 5 5

(6)

extern int j;

void main(){

int i=0;

clrscr();

for(i=0;i<=2;i+=1){

int j=5;

printf("%d ",j);

j++;

}

getch();

}

int j=25;

Output: 5 5 5

C programming language basic questions and answers

Multiple choice questions in c

2012-05-27T13:59:00.002+05:30

Objective questions of c

2012-05-27T13:29:00.000+05:30

Objective type questions on c with answers for interview

C programming language objective questions and answers

(1)

#define max value 10

int main(){

int a=60;

if(a/max value==6)

printf("equal");

else

printf("not equal");

return 0;

}

What will be output if you compile and execute the above code?

(a)equal

(b)not equal

(c)Run time error

(d)Compiler error

(2)

#define num int long

int main(){

num a=0;

printf("%d,%d,%d",a++,sizeof a++,sizeof(a++));

return 0;

}

What will be output if you compile and execute the above code?

(a)3 2 4

(b)0 0 4

(d)Compiler error

(3)

#define short int long

int main(){

printf("%d",sizeof(short));

return 0;

}

What will be output if you compile and execute the above code?

(a)2

(b)4

(d)Compiler error

(4)

#define float char

int main(){

float f=255;

printf("%d",sizeof(f++));

return 0;

}

What will be output if you compile and execute the above code?

(a)1

(b)2

(d)Compiler error

(5)

int main(){

char f=255.0;

printf("%d",sizeof(f++));

return 0;

}

What will be output if you compile and execute the above code?

(a)1

(b)8

(d)Compiler error

(6)

int main(){

char f=255;

f++;

printf("%d",sizeof(f));

return 0;

}

What will be output if you compile and execute the above code?

(a)1

(b)2

(d)Compiler error

(7)

#define value 10\2

int main(){

printf("%d",value);

return 0;

}

What will be output if you compile and execute the above code?

(a)5

(b)20

(d)Compiler error

(8)

#define xxx 11\

int main(){

printf("%ld",xxx);

return 0;

}

What will be output if you compile and execute the above code?

(a)11

(b)3

(d)Compiler error

(9)

#define option1 a++; printf("%d",a);

#define option2 print("%d",a);

int main(){

int a=10;

if(a++)

option1

else

option2;

}

What will be output if you compile and execute the above code?

(a)10

(b)11

(d)Compiler error

(10)

//test.c

int main(){

printf("%s",__FILE__);

}

What will be output if you compile and execute the above code?

(a)null

(b)test.c

(c)url of current working directory

(d)Compiler error

(11)

#include"stdio.h"

int main(){

#ifdef __stdio_h

prinrf("defined");

#else

printf("not defined");

#endif

return 0;

}

What will be output if you compile and execute the above code?

(a) defined

(b) not defined

(c)Run time error

(d)Compiler error

(12)

#include"stdio.h"

int main(){

const int a=1;

#if 5+~5+1

printf("%d",a+1);

#elif 7

printf("%d",a+2);

#else

printf("%d",a+3);

#endif

return 0;

}

What will be output if you compile and execute the above code?

(a)2

(b)3

(d)Compiler error

(13)

#define conio.h

#include "stdio.h"

#define max 0\5

int main(){

#ifndef __conio_h

#define conio.h

printf("%s",__TIME__);

#else

#undef __conio_h

printf("%s",__DATE__);

#endif

return 0;

}

What will be output if you compile and execute the above code?

(a)Output will be date of compilation

(b)Output will be time of compilation

(c)Output will be both time of compilation and date of compilation

(d)Compiler error

(14)

#define max 5

#define a max*max

#define value a\a

int main(){

const int aa=5;

printf("%d",value+aa);

return 0;

}

What will be output if you compile and execute the above code?

(a)5

(b)6

(d)Compiler error

(15)

#define function(a,b) a##b

int main(){

printf("%d",function(5,2));

return 0;

}

What will be output if you compile and execute the above code?

(a)10

(b)2

(d)Compiler error

(16)

#define find(a,b,c) #a#b#c

int main(){

int a=10;

int b=20;

int c=30;

printf("%s",find(a,b,c)+1);

return 0;

}

What will be output if you compile and execute the above code?

(a)102030

(b)02030

(c)bc

(d)Compiler error

(17)

#define swap(x,y) x^=y^=x^=y

int main(){

int a=10,b=20;

swap(a,b);

printf("%d %d" ,a,b);

return 0;

}

What will be output if you compile and execute the above code?

(a)10 20

(b)20 10

(d)Compiler error

(18)

#define int long

#define cal(x,y,z) x*y*z

int main(){

int a=2;

int b=cal(a++,a++,a++);

printf("%d,%d" ,a,b);

return 0;

}

What will be output if you compile and execute the above code?

(a)5,0

(b)5,125

(d)Compiler error

(19)

#define final(a,b,c) ++a+ ++b+ ++c

int main(){

printf("%d" ,final(1,2,3));

return 0;

}

What will be output if you compile and execute the above code?

(a)6

(b)9

(d)Compiler error

(20)

void one();

void two();

#pragma startup one 2

#pragma startup two 1

int main(){

printf("main ");

return 0;

}

void one()

{

printf("one ");

}

void two()

{

printf("two ");

}

What will be output if you compile and execute the above code?

(a)main one two

(b)one main two

(c)main

(d)two main one

Answer of c programming objective types questions and answers

1. (d)

2. (c)

3. (b)

4. (a)

5. (a)

6. (a)

7. (c)

8. (c)

9. (d)

10. (b)

11. (b)

12. (b)

13. (b)

14. (c)

15. (c)

16. (c)

17. (b)

18. (a)

19. (d)

20. (d)

Learn c program esily for beginners online free

2012-05-21T01:25:00.001+05:30

Learn c programming language online free

How to write a code in c?

Write a c program to find the roots of a quadratic equation.

Write a c program to reverse a string.

Write a c program to reverse a number.

Write a c program to print Pascal triangle.

Write a c program that accepts a month and day.

Write a c program for Fibonacci series.

Write a c program to find prime numbers.

Write a c program to multiply two matrices.

Write a c program to convert binary to decimal.

Simple program example in c language

2012-05-21T00:52:00.003+05:30

Basic simple c language programs examples for beginners

C program to print "hello world".

Code

#include<stdio.h>

int main(){

printf("Hello world");

return 0;

}

Hide

C program to add two numbers in c.

Code

#include<stdio.h>

int main(){

int a,b,sum;

scanf("%d %d",&a,&b);

sum = a + b;

printf("%d",sum);

return 0;

}

Hide

C program to accept a string from users and print it.

Code

#include<stdio.h>

int main(){

char str[20];

scanf("%s",&str);

printf("%s",str);

return 0;

}

Hide

C program to check a given number is positive or negative.

Code

#include<stdio.h>

int main(){

int num;

scanf("%d",&num);

if(num ==0)

printf("Number is zero.");

else if(num > 0)

printf("Number is positive.");

else

printf("Number is negative.");

return 0;

}

Hide

C program to swap two numbers.

Code

#include<stdio.h>

int main(){

int a,b,c;

scanf("%d %d",&a,&b);

c = a;

a = b;

b = c;

printf("%d %d",a,b);

return 0;

}

Hide

C program to find area of a circle.

Code

#include<stdio.h>

int main(){

floar r,area;

printf("Enter radius of circle: ");

scanf("%f",&r);

area = 3.14 * r * r;

printf("Area of circle is: %f",area);

return 0;

}

Hide

C program to print numbers from 1 to 10.

Code

#include<stdio.h>

int main(){

int i;

for(i=1;i<=10;i++){

printf("%d ",i);

}

return 0;

}

Hide

C program to print numbers from 1 to 10 in reverse order.

Code

#include<stdio.h>

int main(){

int i;

for(i=10;i>= 0;i--){

printf("%d ",i);

}

return 0;

}

Hide

C program to print all even numbers of the given range.

Code

#include<stdio.h>

int main(){

into min,max;

printf("Enter min and max even numbers respectively: ");

scanf("%d %d",&min,&max);

for(i=min;i<=max;i=i+2){

printf("%d ",i);

}

return 0;

}

Hide

C program to accept a string and find out total numbers of characters.

Code

#include<stdio.h>

#include<string.h>

int main(){

char str[20];

printf("Enter any string: ");

scanf("%s",&str);

printf("Length of string: %d",strlen(str));

return 0;

}

Hide

C program to add n natural numbers from 1.

Code

#include<stdio.h>

int main(){

int n,sum = 0;

printf("Enter any positive number: ");

scanf("%d",&n);

for(i=1;i<=n;i++){

sum = sum + 1;

}

printf("Sum of n numbers: %s",sum);

return 0;

}

Hide

C program to get the marks of student and print the average marks.

Code

#include<stdio.h>

int main(){

int n;

float marks, sum = 0;

printf("Enter any total numbers of student: ");

scanf("%d",&n);

for(i=1;i<=n;i++){

printf("Enter marks of student %d: ",i);

scanf("%f",&marks);

sum = sum + marks;

}

printf("Average marks: %f",sum/n);

return 0;

}

Hide

C program to print the all elements of any array.

Code

#include<stdio.h>

int main(){

int arr[]={1,2,34,56,89};

int i;

for(i=0;i<5;i++){

printf("%d ",arr[i]);

}

return 0;

}

Hide

C program to find square root of a number.

Code

#include<stdio.h>

#include<math.h>

int main(){

int num;

scanf("%d",&num);

printf("Square root: %f",sqrt(num));

return 0;

}

Hide

C program to find max of two unequal numbers.

Code

#include<stdio.h>

int main(){

int a,b,max;

scanf("%d %d",&a,&b);

if(a > b)

max = a;

else

max = b;

printf("%d",max));

return 0;

}

Hide

C program to check given number is even or odd.

Code

#include<stdio.h>

int main(){

int number;

printf("Enter any integer: ");

scanf("%d",&number);

if(number % 2 ==0)

printf("%d is even number.",number);

else

printf("%d is odd number.",number);

return 0;

}

Hide

Write a c program to print multiplication table.

Code

#include<stdio.h>

int main(){

int r,i,j,k;

printf("Enter the number range: ");

scanf("%d",&r);

for(i=1;i<=r;i++){

for(j=1;j<=10;j++)

printf("%d*%d=%d ",i,j,i*j);

printf("\n");

}

return 0;

}

Hide

Code to find the ASCII values of given character in c.

Code

#include<stdio.h>

int main(){

char c;

printf("Enter any character: ");

scanf("%c",&c);

printf("ASCII value of given character: %d",c);

return 0;

}

Hide

C program to convert upper case to lower case.

Code

#include<stdio.h>
#include<string.h>

int main(){

char str[20];

int i;

printf("Enter any string: ");

scanf("%s",str);

printf("The string is: %s",str);

for(i=0;i<=strlen(str);i++){

if(str[i]>=65&&str[i]<=90)

str[i]=str[i]+32;

}

printf("\nThe string in uppercase is: %s",str);

return 0;

}

Hide

C program to convert lower case to upper case.

Code

#include<stdio.h>

int main(){

char str[20];

int i;

printf("Enter any string: ");

scanf("%s",str);

printf("The string is: %s",str);

for(i=0;i<=strlen(str);i++){

if(str[i]>=97&&str[i]<=122)

str[i]=str[i]-32;

}

printf("\nThe string in lowercase is: %s",str);

return 0;

}

Hide

Pointers tutorial in c

2012-03-30T01:09:00.000+05:30

Tricky c questions and answers

2012-02-05T14:40:00.002+05:30

Tricky c programs question for interview and answers with explanation. These questions are for experienced persons.

C advanced interview questions and answers

(1) What will be output if you will compile and execute the following c code?

struct marks{

int p:3;

int c:3;

int m:2;

};

void main(){

struct marks s={2,-6,5};

printf("%d %d %d",s.p,s.c,s.m);

}

(a) 2 -6 5

(b) 2 -6 1

(d) Compiler error

(e) None of these

Answer: (c)

Explanation:

Binary Representation:

Binary value of 2: 00000010 (Choose the last two bits)
Binary value of 6: 00000110
Binary value of -6: 11111001 + 1 = 11111010 (Select the last three bits)
Binary value of 5: 00000101 (Choose the last two bits)

Complete memory representation:

(2) What will be output if you will compile and execute the following c code?

void main(){

int huge*p=(int huge*)0XC0563331;

int huge*q=(int huge*)0xC2551341;

*p=200;

printf("%d",*q);

}

(a)0

(b)Garbage value

(c)null

(d) 200

(e)Compiler error

Answer: (d)

Explanation:

Calculating the Physical Address:

Physical address of huge pointer 'p':
- Huge address: 0xC0563331
- Offset address: 0x3331
- Segment address: 0xC056
- Physical address = Segment address * 0x10 + Offset address = 0xC056 * 0x10 + 0x3331 = 0xC0560 + 0x3331 = 0xC3891
Physical address of huge pointer 'q':
- Huge address: 0xC2551341
- Offset address: 0x1341
- Segment address: 0xC255
- Physical address = Segment address * 0x10 + Offset address = 0xC255 * 0x10 + 0x1341 = 0xC2550 + 0x1341 = 0xC3891

Since both huge pointers 'p' and 'q' are pointing to the same physical address, the content of 'q' will also be the same as the content of 'p.

(3) Write c program which display mouse pointer and position of pointer.(In x coordinate, y coordinate)?

Answer:

#include”dos.h”

#include”stdio.h”

void main()

{

union REGS i,o;

int x,y,k;

//show mouse pointer

i.x.ax=1;

int86(0x33,&i,&o);

while(!kbhit()) //its value will false when we hit key in the key board

{

i.x.ax=3; //get mouse position

x=o.x.cx;

y=o.x.dx;

clrscr();

printf("(%d , %d)",x,y);

delay(250);

int86(0x33,&i,&o);

}

getch();

}

(4) Write a c program to create dos command: dir.

Answer:

Step 1: Write following code.

#include “stdio.h”

#include “dos.h”

void main(int count,char *argv[]){

struct find_t q ;

int a;

if(count==1)

argv[1]="*.*";

a = _dos_findfirst(argv[1],1,&q);

if(a==0){

while (!a){

printf(" %s\n", q.name);

a = _dos_findnext(&q);

}

else{

printf("File not found");

}

Step 2: Save the file as list.c (you can choose any name).

Step 3: Compile and execute the file.

Step 4: Right-click on "My Computer" in the Windows XP operating system and select "Properties."

Step 5: Navigate to Advanced -> Environment Variables.

Step 6: In the window that appears, click on the "New" button (located inside the red box).

Step 7:

Variable name: path
Variable value: c:\tc\bin\list.c (Specify the path where you have saved the file)

Step 8:

Open the command prompt.
Write list and press Enter.
Explore command line argument tutorials.

(6) What will be output if you will compile and execute the following c code?

void main(){

int i=10;

static int x=i;

if(x==i)

printf("Equal");

else if(x>i)

printf("Greater than");

else

printf("Less than");

}

(a) Equal

(b) Greater than

(d) Compiler error

(e) None of above

Answer: (d)

Explanation:

Static variables are considered load-time entities, whereas auto variables are run-time entities. It is not permissible to initialize any load-time variable with a run-time variable. In the context of this example, 'i' is a run-time variable, while 'x' is a load-time variable.

Properties of static variables.

Properties of auto variables.

(7) What will be output if you will compile and execute the following c code?

void main(){

int i;

float a=5.2;

char *ptr;

ptr=(char *)&a;

for(i=0;i<=3;i++)

printf("%d ",*ptr++);

}

(a)0 0 0 0

(b)Garbage Garbage Garbage Garbage

(d)102 102 -90 64

(e)Compiler error

Answer: (d)

Explanation:

In C, the float data type is a four-byte data type, while a char pointer, such as 'ptr,' can point to one byte of memory at a time. Considering the memory representation of the float variable 'a' initialized to 5.2:

The ptr pointer will sequentially point to the fourth, third, second, and first bytes of memory. The content of each byte is as follows:

Content of the fourth byte:
- Binary value: 01100110
- Decimal value: 64 + 32 + 4 + 2 = 102
Content of the third byte:
- Binary value: 01100110
- Decimal value: 64 + 32 + 4 + 2 = 102
Content of the second byte:
- Binary value: 10100110
- Decimal value: -128 + 32 + 4 + 2 = -90
Content of the first byte:
- Binary value: 01000000
- Decimal value: 64

Note: The character pointer treats the Most Significant Bit (MSB) of each byte, i.e., the leftmost bit of the given figure, as the sign bit.

(8) What will be output if you will compile and execute the following c code?

void main(){

int i;

double a=5.2;

char *ptr;

ptr=(char *)&a;

for(i=0;i<=7;i++)

printf("%d ",*ptr++);

}

(a) -51 -52 -52 -52 -52 -52 20 64

(b) 51 52 52 52 52 52 20 64

(d) Compiler error

(e) None of these

Answer: (a)

Explanation:

In C, the double data type is an eight-byte data type, while a char pointer, such as 'ptr,' can point to one byte of memory at a time. Considering the memory representation of the double variable 'a' initialized to 5.2:

The ptr pointer will sequentially point to the eighth, seventh, sixth, fifth, fourth, third, second, and first bytes of memory, as shown in the figure above. The content of each byte is as follows:

Content of the eighth byte:
- Binary value: 11001101
- Decimal value: -128 + 64 + 8 + 4 + 1 = -51
Content of the seventh byte:
- Binary value: 11001100
- Decimal value: -128 + 64 + 8 + 4 = -52
Content of the sixth byte:
- Binary value: 11001100
- Decimal value: -128 + 64 + 8 + 4 = -52
Content of the fifth byte:
- Binary value: 11001100
- Decimal value: -128 + 64 + 8 + 4 = -52
Content of the fourth byte:
- Binary value: 11001100
- Decimal value: -128 + 64 + 8 + 4 = -52
Content of the third byte:
- Binary value: 11001100
- Decimal value: -128 + 64 + 8 + 4 = -52
Content of the second byte:
- Binary value: 000010100
- Decimal value: 16 + 4 = 20
Content of the first byte:
- Binary value: 01000000
- Decimal value: 64

Note: The character pointer treats the Most Significant Bit (MSB) of each byte, i.e., the leftmost bit of the above figure, as the sign bit.

(9) What will be output if you will compile and execute the following c code?

void main(){

printf("%s","c" "question" "bank");

}

(a) c question bank

(b) c

(d) cquestionbank

(e) Compiler error

Answer: (d)

Explanation:

In C, the string constant 'xy' is equivalent to the concatenation of two string constants 'x' and 'y', denoted as 'x' 'y'.

String tutorial.

(10) What will be output if you will compile and execute the following c code?

void main(){

printf("%s",__DATE__);

}

(a) Current system date

(b) Current system date with time

(d) Compiler error

(e) None of these

Answer: (a)

Explanation:

__DATE__ is a global identifier in C that returns the current system date.

(11) What will be output if you will compile and execute the following c code?

void main(){

char *str="c-pointer";

printf("%*.*s",10,7,str);

}

(a) c-pointer

(b) c-pointer

(d) cpointer null null

(e) c-point

Answer: (e)

Explanation:

The format specifier %*.*s in the printf function serves the following purposes:

The first * denotes the width, indicating the number of spaces allocated to print the string.
The second * denotes precision, specifying the number of characters to be printed from any given string.

The output of the code using this format specifier is illustrated in the following figure:

Properties of printf function.

(12) What will be output if you will compile and execute the following c code?

void start();

void end();

#pragma startup start

#pragma exit end

int static i;

void main(){

printf("\nmain function: %d",++i);

}

void start(){

clrscr();

printf("\nstart function: %d",++i);

}

void end(){

printf("\nend function: %d",++i);

getch();

}

(a)

main function: 2

start function: 1

end function:3

(b)

start function: 1

main function: 2

end function:3

(c)

main function: 2

end function:3

start function: 1

(d) Compiler error

(e) None of these

Answer: (b)

Explanation:

Every C program typically begins execution with the main function and concludes with a null statement. However, the #pragma startup directive allows for the invocation of a function just before the main function, and similarly, #pragma exit provides a mechanism to call a function at program termination.

What is pragma directive?

Preprocessor tutorial.

(13) What will be output if you will compile and execute the following c code?

void main(){

int a=-12;

a=a>>3;

printf("%d",a);

}

(a) -4

(b) -3

(d) -96

(e) Compiler error

Answer :( c)

Explanation:

The binary representation of 12 is: 00000000 00001100. To obtain the binary value of -12, one needs to take the 2’s complement of 12, which is:

The binary value of -12, obtained through the 2’s complement of 12, is: 11111111 11110100.

Right Shifting Rule:

Rule 1: If the number is positive, fill vacant spaces on the left side with 0s.
Rule 2: If the number is negative, fill vacant spaces on the left side with 1s.

In this particular case, where the number is negative, perform a right shift of all binary digits by three spaces and fill the vacant spaces on the left side with 1s, as illustrated in the following figure:

Given that it is a negative number, the output will also be negative, represented in 2’s complement form.

Hence final out put will be:

As a result of the right shift and considering its 2’s complement representation, the binary value corresponds to the decimal value of -2. Therefore, the output is indeed -2.

(14) What will be output if you will compile and execute the following c code?

#include "string.h"

void main(){

clrscr();

printf("%d%d",sizeof("string"),strlen("string"));

getch();

}

(a) 6 6

(b) 7 7

(d) 7 6

(e) None of these

Answer: (d)

Explanation:

The sizeof operator in C returns the size of the entire array, including the null character ('\0'), for a string declared as an array of characters. On the other hand, the strlen function from the <string.h> library returns the length of the string, excluding the null character.

(15) What will be output if you will compile and execute the following c code?

void main(){

static main;

int x;

x=call(main);

clrscr();

printf("%d ",x);

getch();

}

int call(int address){

address++;

return address;

}

(a) 0

(b) 1

(d) Compiler error

(e) None of these

Answer: (b)

Explanation:

While 'main' is not a reserved keyword in C, it holds a special significance as the entry point for program execution. The term 'main' can also be used as a variable name within the 'main' function and other functions.

What is main function in c?

(16) What will be output if you will compile and execute the following c code?

void main(){

int a,b;

a=1,3,15;

b=(2,4,6);

clrscr();

printf("%d ",a+b);

getch();

}

(a) 3

(b) 21

(d) 7

(e) Compiler error

Answer: (d)

Explanation:

In C, the comma serves a dual purpose as both a separator and an operator. In the expressions:

a=1, 3, 15;

b= (2, 4, 6);

The comma acts as an operator. The comma operator enjoys the lowest precedence among operators, and its associativity is from left to right. Assigning the priority of each operator in the first statement:

Hence, in the first statement, the value 1 will be assigned to 'a'.

Now, assigning the priority of each operator in the second statement:

(17) What will be output if you will compile and execute the following c code?

int extern x;

void main()

printf("%d",x);
x=2;

getch();

}

int x=23;

(a) 0

(b) 2

(d) Compiler error

(e) None of these

Answer: (c)

Explanation:

Extern variables in C enable the program to locate the declaration of a variable anywhere in the program. This provides flexibility in accessing variables declared outside the current scope or file.

(18) What will be output if you will compile and execute the following c code?

void main(){

int i=0;

if(i==0){

i=((5,(i=3)),i=1);

printf("%d",i);

}

else

printf("equal");

}

(a) 5

(b) 3

(d) equal

(e) None of above

Answer: (c)

Explanation:

(19) What will be output if you will compile and execute the following c code?

void main(){

int a=25;

clrscr();

printf("%o %x",a,a);

getch();

}

(a) 25 25

(b) 025 0x25

(d) 31 19

(e) None of these

Answer: (d)

Explanation:

The format specifier %o is used in C to print numbers in octal format, while %x is used to print numbers in hexadecimal format. It's important to note that in C, octal numbers are denoted by a leading 0, and hexadecimal numbers start with '0x'.

(20) What will be output if you will compile and execute the following c code?

#define message "union is\

power of c"

void main(){

clrscr();

printf("%s",message);

getch();

}

(a) union is power of c

(b) union ispower of c

Power of c

(d) Compiler error

(e) None of these

Answer: (b)

Explanation:

If you wish to write a macro constant across multiple lines, it can be concluded with the character ".This indicates a continuation of the macro definition onto the next line.

(21) What will be output if you will compile and execute the following c code?

#define call(x) #x

void main(){

printf("%s",call(c/c++));

}

(a)c

(b)c++

(c)#c/c++

(d)c/c++

(e)Compiler error

Answer: (d)

Explanation:

The '#' symbol in C is known as the stringizing operator. It converts the macro function call argument into a string. For example, consider the following lines in the intermediate file:

test.c 1:

test.c 2: void main(){

test.c 3: printf("%s","c/c++");

test.c 4: }

test.c 5:

It's evident that the macro call is replaced by its argument in string format during preprocessing.

(22) What will be output if you will compile and execute the following c code?

void main(){

if(printf("cquestionbank"))

printf("I know c");

else

printf("I know c++");

}

(a) I know c

(b) I know c++

(d) cquestionbankI know c++

(e) Compiler error

Answer: (c)

Explanation:

The return type of the printf function in C is an integer, representing the number of characters it prints, including blank spaces. In the context of an if condition, the printf function will return 13. In C, any non-zero value is considered true, so the else part will not be executed.

If you have any doubts regarding the explanations provided for the above tricky questions, feel free to ask in the comment section.

C programming online test

2012-02-05T14:32:00.002+05:30

C programming online test questions answers and explanation for freshers

These are objective type questions and answers for a C programming language online test or quiz, designed for interviews or written tests. If you have any queries or suggestions, please feel free to share them.

(A)	320
(B)	1
(C)	64
(D)	Compiler error
(E)	None of above

(A)	343
(B)	27
(C)	133
(D)	Compiler error
(E)	None of above

(A)	135
(B)	+INF
(C)	-121
(D)	-8
(E)	Compiler error

(A)	It will print nothing.
(B)	-3
(C)	-2
(D)	1
(E)	Compiler error

(A)	12 11 11
(B)	12 10 10
(C)	11 11 12
(D)	10 10 12
(E)	Compiler error

(A)	Equal
(B)	Less than
(C)	Greater than
(D)	Compiler error
(E)	None of above

(A)	11Hello world
(B)	10Hello world
(C)	Hello world10
(D)	Hello world11
(E)	Compiler error

(A)	cquestionbank
(B)	cquestionbank\0
(C)	(null)
(D)	It will print nothing
(E)	Compiler error

(A)	Nesting of structure is not allowed in c.
(B)	It is necessary to initialize the member variable.
(C)	Inner structure must have name.
(D)	Outer structure must have name.
(E)	There is not any error.

Topic:		Total questions:
Total marks:		Correct answer:
Total time:		Incorrect answer:
Passing Marks:

(A)	10 11 12 13 14
(B)	10 10 10 10 10
(C)	0 1 2 3 4
(D)	Compilation error

(A)	0
(B)	It will be difference of a and b
(C)	It will be addition of a and b
(D)	Compilation error

Total correct answers:
Total incorrect answers:
Total not attempted questions:
Marks obtained:
Result: