Techabaya

Nested structures in C

2020-04-15T23:27:00.001+05:30

When a structure contains another structure as its member, it is called a nested structure.

Syntax:

struct innerStruct{

-------------------

};

struct outerStruct{

-------------------

struct innerStruct inner;

};

For example, we want to store information about an employee-empName, empNo, dept,address. Address can be broken into houseNo,city,pincode so we will store address details in another structure named Address and other information about employee in Employee structure.

#include<stdio.h>

//Inner structure

struct Address{

char houseNo[20];

char city[20];

};

//Outer structure

struct Employee{

char empName[25];

char dept[15];

struct Address add;

};

int main(){

struct Employee emp;

printf("Enter Employee Name: ");

scanf("%s",&emp.empName);

printf("Enter Employee Department: ");

scanf("%s",&emp.dept);

printf("Enter Employee Address details:\n ");

printf("Enter Employee House No: ");

scanf("%s",&emp.add.houseNo);

printf("Enter Employee City: ");

scanf("%s",&emp.add.city);

printf("\nEmployee Details\n");

printf("Name :%s\n",&emp.empName);

printf("Department :%s\n",&emp.dept);

printf("House No :%s\n",&emp.add.houseNo);

printf("City :%s\n",&emp.add.city);

return 0;

}

Output:

Note that inner structure must be declared before outer structure.

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Dynamic memory allocation in C language with example

2020-04-13T20:14:00.000+05:30

Dynamic memory allocation in C is performed using one of the standard library functions

malloc, calloc or realloc. Dynamically allocated memory must eventually be freed by calling free. If allocated memory is not properly freed a memory leak results, which could result in a program malfunction.

All these functions are in header file <stdlib.h>.

The malloc() function

This function allocates specified number of bytes.

It takes a single argument.

It does not initialize the allocated memory.

It returns a pointer of type void which can be cast into a pointer of any form.

If space is insufficient, allocation fails and returns a NULL pointer.

Syntax:

ptr=(cast_type *) malloc(sizeof(type))

Example:

int *ptr;

ptr=(int *) malloc(sizeof(int));

ptr points to memory allotted by malloc() function.

The calloc() function

This function allocates specified number of bytes.

It takes two arguments.

It initializes each block allocated memory with a default value of 0.

It returns a pointer of type void which can be cast into a pointer of any form.

If space is insufficient, allocation fails and returns a NULL pointer.

Syntax:

ptr=(cast_type *) calloc(n,sizeof(type))

where

n= no of elements

sizeof(type) return no of bytes to be allotted

Example:

int *ptr;

ptr=(int *) calloc(n,sizeof(int));

ptr points to memory allotted by calloc() function.

The realloc() function

If someone wants to modify the memory allotted by malloc() and calloc() functions, this function can be used to do this.

Syntax:

ptr=(cast_type*) realloc(ptr,sizeof(type))

Example:

int *ptr;

ptr=(int *) malloc(sizeof(int));

ptr=(int*) realloc(ptr,newSize);

The free() function

Memory allotted using malloc() and calloc() functions should be freed. It helps to reduce wastage of memory.

Syntax:

free(pointer_variable);

Example:

int *ptr;

ptr=(int *) malloc(sizeof(int));

free(ptr);

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Passing Structure to a Function in C with Example

2020-04-06T23:33:00.001+05:30

Like other variables, we can also pass individual members of a structure and whole structure also ( structure variable).

First, let us see how to pass individual members of a structure.

Program 1 : Passing individual members of a structure to a function

#include<stdio.h>

//structure declaration

struct student{

int rollno;

float marks;

};

int display(int roll, float mrk){

printf("\nRoll no : %d\tMarks : %.2f\n\n",roll,mrk);

}

int main(){

struct student s;

s.rollno=123;

s.marks=95.5;

display(s.rollno,s.marks);

return 0;

}

Output:

Roll no : 123 Marks : 95.50

Program 2 : Passing structure variable to a function : Call by Value

#include<stdio.h>

//structure declaration

struct student{

int rollno;

float marks;

};

int display(struct student ss){

printf("\nRoll no : %d\tMarks : %.2f\n\n",ss.rollno,ss.marks);

}

int main(){

struct student s;

s.rollno=123;

s.marks=95.5;

display(s);

return 0;

}

Output:

Roll no : 123 Marks : 95.50

Program 3 : Passing structure variable to a function : Call by Reference

#include<stdio.h>

//structure declaration

struct student{

int rollno;

float marks;

};

int display(struct student *ss){

printf("\nRoll no : %d\tMarks : %.2f\n\n",ss->rollno,ss->marks);

}

int main(){

struct student s;

s.rollno=123;

s.marks=95.5;

display(&s);

return 0;

}

Output:

Roll no : 123 Marks : 95.50

Note that when accessing structure members by pointer to a structure, we ->(arrow operator) not dot(.) operator.

You may also like:
Structure in C
Typedef in C with examples
Array of Structures in C with Example
Self Referential Structures in C

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Self Referential Structures in C with example

2020-04-06T16:38:00.002+05:30

A Self Referencial Structure is a structure which have one or more pointer variables of that structure type as their member(s).

Consider following example:

struct student{

int rollno;

float marks;

};

Above structure declaration is standard declaration we studied earlier. But if we add one or more pointer variables of structure student type as the member(s) of student structure, then it will become self referencial structure. See the example below:

struct student{

int rollno;

float marks;

struct student *next;

}

In the above example ‘next’ is a pointer to a structure of type ‘student. Hence, the structure ‘student is a self-referential structure with ‘next as the referencing pointer.

A self referential structure is used to create data structures like linked lists, stacks, queues etc.

You may also like:
Structure in C
Typedef in C with examples
Array of Structures in C with Example

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Array of Structures in C with example

2020-04-05T12:40:00.001+05:30

Like normal arrays of integer, floats etc which have elements of type integer, float respectively, array of structures is nothing but a collection of structures. It means elements of array will be structures not normal type ( integer, float etc.).

Consider following example:

#include<stdio.h>

struct student{

int rollno;

float marks;

};

int main(){

struct student s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

return 0;

}

In above program, we have declared one structure variable s1 for one student. What if we want to store roll no and marks of 40 students of a class? We have two options either we declare 40 structure variables (s1 to s40) or simply create an array of structures of size 40 as explained in below program:

#include<stdio.h>

struct student{

int rollno;

float marks;

};

int main(){

struct student s[5];

int i;

printf("\nEnter Students Details\n");

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

printf("\nEnter Roll No and marks of student %d\n",i+1);

scanf("%d",&s[i].rollno);

scanf("%f",&s[i].marks);

}

printf("\nStudents Details\n");

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

printf("\nRoll No and marks of student %d are %d and %f respectively\n",i+1,s[i].rollno,s[i].marks);

}

return 0;

}

Output:

You may also like:
Structure in C
Typedef in C with examples
Self Referential Structures in C with Example

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Typedef in C with examples

2020-04-03T23:32:00.002+05:30

Consider following example:

#include<stdio.h>

struct student{

int rollno;

float marks;

};

int main(){

struct student s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

struct student s2;

s2.rollno=13;

s2.marks=90;

printf("\nStudent 2 Details\n");

printf("\nRoll No:%d",s2.rollno);

printf("\nMarks:%.2f\n",s2.marks);

return 0;

}

As you can see in above example, every time, a structure variable is being declared, we have to write struct student varName.

To avoid writing struct all over the place, we can use typedef with structure declaration. Using a typedef avoids having to write struct every time you declare a variable of that type.

Example:

#include<stdio.h>

typedef struct student{

int rollno;

float marks;

};

int main(){

student s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

student s2;

s2.rollno=13;

s2.marks=90;

printf("\nStudent 2 Details\n");

printf("\nRoll No:%d",s2.rollno);

printf("\nMarks:%.2f\n",s2.marks);

return 0;

}

Another version of above program:

#include<stdio.h>

typedef struct {

int rollno;

float marks;

}student;

int main(){

student s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

student s2;

s2.rollno=13;

s2.marks=90;

printf("\nStudent 2 Details\n");

printf("\nRoll No:%d",s2.rollno);

printf("\nMarks:%.2f\n",s2.marks);

return 0;

}

Another version of same program:

#include<stdio.h>

struct student{

int rollno;

float marks;

};

typedef struct student;

int main(){

student s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

student s2;

s2.rollno=13;

s2.marks=90;

printf("\nStudent 2 Details\n");

printf("\nRoll No:%d",s2.rollno);

printf("\nMarks:%.2f\n",s2.marks);

return 0;

}

Another version of above program:

#include<stdio.h>

struct student{

int rollno;

float marks;

};

typedef struct student s;

int main(){

s s1;

s1.rollno=12;

s1.marks=92.5;

printf("\nStudent 1 Details\n");

printf("\nRoll No:%d",s1.rollno);

printf("\nMarks:%.2f\n",s1.marks);

s s2;

s2.rollno=13;

s2.marks=90;

printf("\nStudent 2 Details\n");

printf("\nRoll No:%d",s2.rollno);

printf("\nMarks:%.2f\n",s2.marks);

return 0;

}

Summary:

(i). Typedef keyword is used to give a new symbolic name(i.e alias) to another existing type.

(ii). It saves some typing.

(iii). It makes code cleaner.

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How to read deleted WhatsApp messages

2020-03-26T14:58:00.001+05:30

WhatsApp allows users to delete a sent message within a stipulated time. However, there is a way to read deleted messages. But one must remember that there is no such official feature which let you read deleted messages.

To read deleted WhatsApp messages, one will need to download third-party applications. Kindly note that these application might collect personal data stored in the phone. So download such applications at your own risk. One such application is WhatsRemoved+. You can download this app from Google Play store. It is a free app.

Steps

Connect your phone to a WiFi network.

Download WhatsRemoved+ from Google Play store.

Install it and accept the terms and conditions.

Provide access to phone’s notification

App will ask to choose the applications you want it to save all messages from. Select WhatsApp option and then continue.

WhatsRemoved+ will then ask whether it should save files or not. Choose the option that you want.

Then you will be taken to a page that will show all deleted WhatsApp messages. Just click on WhatsApp option on top of the screen.

Hope it helps. Kindly like and share this article.

How to block /unblock USB Ports in Windows

2020-03-20T21:28:00.003+05:30

USB ports are ports are used for different purposes like data transfer between your computer and external hard disk or pen drive.

Disabling USB is one of the best way to stop unauthorized access to your data. Also it stops your computer from viruses which may come from infected flash drives.

In this article, you will learn different ways to block/unblock USB ports in Windows:

Method 1: Using Registry Editor

Step 1: Go to Registry Editor- Windows key + R and type regedit and hit Enter.

Step 2: Go to HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> services -> USBSTOR

Step 3: In the USBSTOR, find the Start DWORD.

Step 4:Double click Start to edit the value.

Change the value data to 4 and the click OK button.

Close Registry Edit.

You are done.

How to reverse a string in Java

2019-08-25T14:56:00.000+05:30

Java is one of the most widely used programming languages in the world and hence a lot of questions are asked in interview from Java.

In this article, you will learn simple but most commonly asked Java Interview Question- How to reverse a string.
You will learn three method to reverse a string.
/*
There is an API for reversing a string in Java. StringBuffer and StringBuilder provides reverse()
method to reverse a string.
*/
package programs;

public class ReverseString {

public static void main(String[] args) {
/*************************method 1- Manual Method********************/
String str = "India";
String revStr = "";

//Convert String to char array
char[] strArray = str.toCharArray();

//find length of char array
int len = strArray.length;

//iterate over char array from last index to first index
for (int i = len - 1; i >= 0; i--) {
revStr = revStr + str.charAt(i);
}
System.out.println("Method 1 : Manually reversing a string");
System.out.println(revStr);

/*************************method 2 - Using StringBuffer********************/
StringBuffer sbf=new StringBuffer(str);
System.out.println("Method 2 : Reverse string using StringBuffer");
System.out.println(sbf.reverse());

/*************************method 3 - Using StringBuilder********************/
StringBuilder sbl=new StringBuilder(str);
System.out.println("Method 3 : Reverse string using StringBuilder");
System.out.println(sbl.reverse());
}

}

Output:

Method 1 : Manually reversing a string

aidnI

Method 2 : Reverse string using StringBuffer

aidnI

Method 3 : Reverse string using StringBuilder

aidnI

How to setup auto login in Windows

2019-05-22T20:17:00.003+05:30

There may be several reasons for you to setup auto login in your computer. Like when you are away from your computer and for some reason you computer restarts and you want to start a program without login into it. But before setting up auto login into your computer, you must that somebody might get physical access to your important data.

If you are sure that nobody has physical access to your computer or data in your computer is not sensitive, then following the procedure below to configure automatic log on to windows.

Step 1: Type netplwiz in Run program.

It will open Advanced User Accounts program.

Step 2: In User Accounts popup, go to Users tab and Uncheck the box next to “Users must enter a username and password to use this computer”.

Step 3 : Click Apply button. Another popup will come up. Enter username and password of user account which you want to setup for automatic log in.

Step 4 : Click Ok button.

You are done. Restart your computer and see whether windows logs in automatically.

Please comment if you find anything incorrect, or you want to improve the topic discussed above.

Type Conversion and Typecasting In C

2019-05-07T17:48:00.002+05:30

Introduction

In our C programs, an expression may contain data values of different data types. When the expression contains values of similar type values then no conversion is required. But if the expression contains values of different types then they must be converted to desired type. In a c programming language, the data conversion is performed in two different methods as follows:

(i).Type Conversion

(ii).Type Casting

Type Conversion

In this procedure, a data value from one data type to another data type is converted automatically by the compiler.

Also known as implicit type conversion.

The implicit type conversion is automatically performed by the compiler.

To evaluate the expression, the data type is promoted from lower to higher level where the hierarchy of data types can be given as: double, float, long, int, short, and char.

Example:

#include<stdio.h>

int main(){

int x=3,u;

float y,v=4.59;

y= x;

u=v;

printf("y=%f\n",y);

printf("u=%d\n",u);

return 0;

}

Output:

y=3.000000

u=4 //data loss

Typecasting

also called as explicit type conversion or forced conversion.

Implicit type conversion may lead to data loss as in above example. That’s why we need type casting.

To convert data from one type to another type we specify the target data type in paranthesis as a prefix to the data value that has to be converted.

Type casting can be done by placing the destination data type in parentheses followed by the variable name that has to be converted.

The general syntax of type casting is as follows:

(data/Type) variableName

Example:

#include<stdio.h>

int main(){

int x=3;

float y;

y= (float)x;

printf("y=%f\n",y);

return 0;

}

Output:

Y=3.000000

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Relational Operators in C

2019-05-05T15:27:00.004+05:30

Relational operators are used to compare two values. There are six relational operators in C. These are called relational operator because they establish relation between its operands. These operators are used in decision-making. These are binary operators because they need two operands.

Following table lists the six relational operators and their meaning-

Sl No	Operator	Syntax	Meaning
1	<	Op1<Op2	Is Op1 less than Op2
2	<=	Op1<=Op2	Is Op1 less than or equal to Op2
3	>	Op1>Op2	Is Op1 greater than Op2
4	>=	Op1>=Op2	Is Op1 greater than or equal to Op2
5	==	Op1==Op2	Is Op1 equal to Op2
6	!=	Op1!=Op2	Is Op1 not equal to than Op2

Each of these operations results in a value of type int. The result of each operation is 1 if the comparison is true and 0 if the comparison is false.

Following C program demonstrates the working of above relational operators-

#include<stdio.h>

int main(){

int a=1,b=2;

if(a<b){

printf(“a is less than b.\n”);

}

a=3,b=2;

if(a<=b){

printf(“a is less than or equal to b.\n”);

}

a=2,b=1;

if(a>b){

printf(“a is grater than b.\n”);

}

a=2,b=3;

if(a>=b){

printf(“a is greater than or equal to b.\n”);

}

a=4,b=4;

if(a==b){

printf(“a is equal to b.\n”);

}

if(a!=b){

printf(“a is not equal to b.\n”);

}

return 0;

}

Output:

a is less than b.

a is grater than b.

a is equal to b.

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The Conditional Operator in C

2019-05-02T10:43:00.000+05:30

Introduction

It involves three operands- the logical expression plus two other expressions—this operator is also referred to as the ternary operator.
The conditional operator evaluates to one of two expressions, depending on whether a logical expression evaluates true or false.

Syntax

Condition ? expression1 : expression2

The ? character follows the logical expression, condition. On the right of ? are two operands, expression1 and expression2, that represent choices. The value that results from the operation will be the value of expression1 if condition evaluates to true, or the value of expression2 if condition evaluates to false. Remember that only one, either expression1 or expression2, will be evaluated.

Example

The conditional operator can be used in place of if-else statements.

Following program find the greater number between two numbers using if-else statements.

#include<stdio.h>

int main(){

int num1=20,num2=30;

if(num1>num2)

printf(“%d is greater than %d.”,num1,num2);

else

printf(“%d is greater than %d.”,num2,num1);

return 0;

}

Output:

30 is greater than 20.

Now we will find out the greater number using conditional operator.

#include<stdio.h>

int main(){

int num1=20,num2=30;

num1>num2?printf(“%d is greater than %d.”,num1,num2):printf(“%d is greater than %d.”,num2,num1);

return 0;

}

Output:

30 is greater than 20.

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Logical Operators in C

2019-05-02T08:07:00.002+05:30

Introduction

Sometimes you want to perform more than one test for a decision. You may want to combine two or more checks on values and perform a certain action only when they’re all true. For example, you may only want to go to watch a movie if you’re feeling well and it’s a weekend. These sorts of situations demand use of logical operators.

There are three logical operators available in C - &&,|| and !.

1. Logical AND && Operator

binary operator that combines two logical expressions—that is, two expressions that evaluate to true or false.
Returns true when both the conditions are true; return false when any of the conditions or both are false.

Syntax :

Expression1 && Expression2

This expression evaluates to true if both expressions Expression1 and Expression2 evaluate to true. If either or both of the expressions are false, the result of the operation is false.

Example:

if(marks >=60 && age < =80)

printf("Grade : B\n");

2. Logical OR || Operator

binary operator that combines two logical expressions—that is, two expressions that evaluate to true or false.
If either or both expressions of the || operator are true, the result is true. The result is false only when both operands are false.

Syntax :

Expression1 || Expression2

This expression evaluates to true if either or both expressions Expression1 and Expression2 evaluate to true. If both expressions are false, the result of the operation is false.

Example:

if(marks >=60 || age < =80)

printf("Grade : B\n");

3. Logical NOT ! Operator

The ! operator is a unary operator, because it applies to just one operand.
The logical NOT operator reverses the value of a logical expression: true becomes false, and false becomes true

Syntax :

!(expression)

If expression is true, it becomes false; if it is false, it becomes true.

Example:

int marks=100;

if(!marks)

printf("You didn’t received 100% marks.\n");

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Increment and decrement operators in C

2019-04-28T09:14:00.003+05:30

Increment Operators are used to increase the value of the variable by one and Decrement Operators are used to decrease the value of the variable by one in C programs.

Both increment and decrement operator are used on a single operand or variable, so it is called as a unary operator. Unary operators are having higher priority than the other operators it means unary operators are executed before other operators.

There are two special unary operator in C/C++, called increment(++) and decrement(--) operators that changes the value of variable by a unit.

Syntax:

Increment Operator : ++

Decrement Operator : --

Example:

int i=1;

i++;

then i=2

int j=5;

j--;

then j=4

Note :

i++ is same as i=i+1;

j-- is same as j=j-1;

Types of Increment Operator :

(a).Post Increment: varName ++

In post increment statement, first use the value of variable and then increment it.

For example;

int i=1;

int x= i++ + i;

Output:

x=2

(b).Pre Increment : ++varName

In pre increment statement, first increment and then use its value after completion of equation.

For example;

int i=1;

int x= ++i + i;

Output:

x=4

Types of Decrement Operator :

(a).Post Decrement : varName--

In post decrement statement, first use the value of variable and then decrement it.

For example;

int i=5;

int x= i-- + i;

Output:

x=10

(b).Pre Decrement : --varName

In post decrement statement, first decrement and then use its value after completion of equation.

For example;

int i=5;

int x= --i + i;

Output:

x=8

Complete Example:

#include<stdio.h>

int main(){

int i=1,j=1,k=5,l=5,x1,x2,y1,y2;

// printf("X1=%d\n",++(i+j));

x1=i++ + i;

printf("I=%d,X1=%d\n",i,x1);

x2=++j + j;

printf("J=%d,X2=%d\n",j,x2);

y1=k-- + k;

printf("K=%d,Y1=%d\n",k,y1);

y2=--l + l;

printf("L=%d,Y2=%d\n",l,y2);

return 0;

}

Output:

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Functions in C(Part 2-Parameter Passing Methods)

2019-04-04T22:55:00.000+05:30

In the previous article, you learnt basics of functions in C. In this article, you will learn about methods of passing values.

Passing values to function

There are two ways to pass arguments/parameters to function calls -- call by value and call by reference.

(i). Pass by value

(ii). Pass by reference

(i).Pass by Value

In this method of parameter passing, a copy of actual parameters is passed to respective formal parameters. Any changes done in formal parameters are not reflected in actual parameters.

When a function is called, any arguments that are provided by the caller are simply treated as expressions. The value of each expression has the appropriate conversions applied and is then used to initialize the corresponding formal parameter in the called function, which behaves in exactly the same way as any other local variables in the function.

The initialization of the formal parameters is the last time that any communication occurs between the caller and the called function, except for the return value.

Example:

//Following example shows the functioning of call by value method

#include<stdio.h>

void swapCallByValue(int,int); //function prototype

int main(){

int num1=10,num2=20;

printf("Values before swapping by call by value: num1=%d,num2=%d.\n",num1,num2);

swapCallByValue (num1,num2);

printf("Values after swapping by call by value: num1=%d,num2=%d.\n\n",num1,num2);

return 0;

}

//function definition: using third variable

void swapCallByValue (int n1,int n2){

int temp;

temp=n1;

n1=n2;

n2=temp;

printf("Inside swapCallByValue : num1=%d,num2=%d\n",n1,n2);

}

Output:

Values before swapping by call by value: num1=10,num2=20.

Inside swapCallByValue : num1=20,num2=10

Values after swapping by call by value: num1=10,num2=20.

(ii).Pass by Reference

In call by reference method of parameter passing, the memory address of actual parameters is passed to formal parameters, hence any change made to formal parameters will also reflected in actual parameters.

This method of parameter passing is use-

(a).If the size of data is large.

(b).When there are more than one value we want to alter.

Example:

//Following example shows the functioning of call by reference method

#include<stdio.h>

void swapCallByReference(int *,int *); //function prototype

int main(){

int num1=10,num2=20;

printf("Values before swapping by call by reference: num1=%d,num2=%d.\n",num1,num2);

swapCallByReference (&num1,&num2);

printf("Values after swapping by call by reference: num1=%d,num2=%d.\n\n",num1,num2);

return 0;

}

//function definition: using third variable

void swapCallByReference (int *n1,int *n2){

int temp;

temp=*n1;

*n1=*n2;

*n2=temp;

printf("Inside swapCallByReference : num1=%d,num2=%d\n",*n1,*n2);

}

Output:

Values before swapping by call by reference: num1=10,num2=20.

Inside swapCallByReference : num1=20,num2=10

Values after swapping by call by reference: num1=20,num2=10.

Points to note about Functions

(a).The name of a function is always followed by ( ).

(b).The keyword void is used in the example to show the function has no return

value and no parameters.

(c).When no return type is specified, it is assumed to be int.

(d).The main program is also a function. It is called the driver function.

(e).The program always starts at the beginning of main, regardless of whether it is

the first function defined or not.

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Functions in C (Part 1-Introduction)

2019-04-04T12:27:00.001+05:30

Introduction to Functions

A function is an independent module or block of program code which deals with a particular task. A function can be called or used anywhere in the program by calling the name.

Each function has a name or identifier by which is used to refer to it in a program. A function can accept a number of parameters or values which pass information from outside, and consists of a number of statements and declarations, enclosed by curly braces { }, which make up the doing part of the object.

The main is a special function called at the beginning of the program. All other functions are directly or indirectly called from main. That’s why main function is called driver function.

Reasons for using functions

There are many reasons for using functions.

(i).Reusability: A function can be reused in many different contexts without repeating parts of the program text.

(ii).Manageability: Using functions, program will be divided to separate blocks. Each block will do a specific job Designing, understanding and managing smaller blocks of code is easier.

(iii).Readability : Since each function has few lines of code which is easy to read and understand.

Parts of a function

(i).Function prototype

(ii).Function Definition

(iii).Function Calling

(i).Function Prototype / Function Declaration

If we want to use a function before we define it, we must declare it just like a variable to inform the compiler about the function. This declaration is called the function prototype.

The point at which a name has a type associated with it. No storage is reserved at this point.

Syntax:

returnType functionName(dataType var1, dataType var2,……,dataType varN);

The variable names are not required when declaring a function prototype.

returnType functionName(dataType, dataType,……,dataType);

Examples:

int square(int number);

void display(void);

(ii).Function Definition

The block of code between braces following the function header is called the function body.

The function header defines the name of the function, the function parameters (which specify the number and types of values that are passed to the function when it’s called), and the type for the value that the function returns.

The function body contains the statements that are executed when the function is called, and these have access to any values that are passed as arguments to the function.

The general form of a function looks like this:

Return_type Function_name( Parameters - separated by commas )

{

// Statements...

}

Also a declaration, but at this point some storage is reserved for the named object.

The arguments used in the function definition are called formal parameters.

Example:

int square(int num){

int result;

result=num*num;

return result;

}

(iii).Calling a function

A function is called (i.e. control is passed to the function) by using its name with the usual brackets () to follow it, along with the values which are to be passed to the function.

When a function is called, the statements within the body of that function are executed, and when the function has finished executing, control returns to the point at which that function was called.

Syntax:

functionName(parameters);

The arguments used when the function is actually called are called actual parameters. In other words, the values that the formal parameters will have on entry to the function.

Example:

int res=square(number);

Complete example

#include<stdio.h>

//function prototype

int square(int number);

int main(){

int number,res;

printf("Enter an integer:\t");

scanf("%d",&number);

//functional calling

res=square(number);

printf("\nSquare of %d is %d.\n",number,res);

return 0;

}

//function definition

int square(int num){

int result;

result=num*num;

return result;

}

How function works?

Program execution start from main function. Statements are executed in sequence in the normal way until a function call is found.

When function call is found, control passes to function definition along with parameter values and statement with in the called function are executed.

Execution of the program continues through the function statements until it encounters a return statement or reaches the closing brace marking the end of the function body. The return statement of closing brace ‘}’ indicates the end of function and control passes to the point immediately after the point the function was originally called.

A Function can different forms:-

Type 1: No return type, no argument

void functionName(void){

//function body

}

Type 2 : return type, no argument

dataType functionName(void){

//function body

return variable;

}

Type 3 : return type, with argument list

dataType functionName(argument list){

//function body

return variable;

}

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Top free stock photo sites for your blog

2019-04-03T11:35:00.001+05:30

Looking for photos for your blog, presentation,magazine without worrying for copyright, here we present top free stock photo sites for you.

1.Pixabay

Pixabay is a vibrant community of creatives, sharing copyright free images and videos. All contents are released under the Pixabay License, which makes them safe to use without asking for permission or giving credit to the artist - even for commercial purposes.

2.Unsplash

Over 850,000 free (do-whatever-you-want) high-resolution photos brought to you by the world’s most generous community of photographers.

3. StockSnap

StockSnap offer beautiful, high quality stock photos for just about any use you can think of - including commercial usage - for free. No tricks, no gimmicks, no fine print; just dazzling images for your creative projects.

4.Pexels

Pexels provides high quality and completely free stock photos licensed under the Pexels license. All photos are nicely tagged, searchable and also easy to discover through our discover pages.

5.PicXclicX

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C Programming Break and Continue statements

2019-03-31T17:52:00.000+05:30

The break and continue statements in C language are used to alter the normal flow of execution of program.

Break statement

Used with loops and switch statements
When encountered, it breaks the execution of block in which break statement is used and program execution starts from the first statement flowing the block in which break statement is used.

Example:

#include<stdio.h>

int main(){

int arr[5]={10,8,9,6,5};

int i,key=9;

//use of break statement

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

if(arr[i]==key){

printf("Element %d found at index %d.\n",key,i);

break;

}

return 0;

}

Output:

Continue statement

Used with loops.
Usually used with if statement
When encountered, it breaks the execution of current iteration and start next iteration.

Example:

#include<stdio.h>

int main(){

int arr[5]={10,8,9,6,5};

int i,key=9;

//use of continue statement

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

if(i%2==0){

continue;

}

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

}

return 0;

}

Output:

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C Loops - For loop, while loop and do while loop

2019-03-29T11:11:00.000+05:30

You may encounter situations, when a block of code needs to be executed several number of times. A loop is used for executing a block of statements repeatedly until a given condition returns false.

There are three types of loop constructs in C. These are as follows-

(1). for loop

(2). while loop

(3). do while loop

(1).for loop

It is used mainly when number of iterations (number of times loop will execute) are known beforehand.

Syntax of for loop

The for loop can be written in several ways.

Syntax 1:

for(initialization;test_condition;updateStatement){

//loop body

}

Syntax 2:

Initialization;

for(;test_condition;updateStatement){

//loop body

}

Syntax 3:

initialization

for(;test_condition;){

//loop body

updateStatement;

}

Note : updateStatement means increment or decrement statement

How for loop works?

The initialization statement is executed only once.
Then, the test_condition is evaluated. If the test_condition is false (0), for loop is terminated.
But if the test_condition is true (nonzero), codes inside the body of for loop is executed and the updateStatement is updated.

This process repeats until the test_condition is false.

Examples:

//program to print integer number from 1 to 10 in ascending order

#include<stdio.h>

void main(){

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

printf(“%d\t”,i);

}

Output: 1 2 3 4 5 6 7 8 9 10

//program to print integer number from 1 to 10 in descending order

#include<stdio.h>

void main(){

for(int i=10;i>=1;i--){

printf(“%d\t”,i);

}

Output: 10 9 8 7 6 5 4 3 2 1

(2). While loop

The while statement is used when the program needs to perform repetitive tasks.

The general form of a while statement is:

while (condition){

statement;

}

The program will repeatedly execute the statement inside the while until the condition becomes false (0). (If the condition is initially false, the statement will not be executed.)

How while loop works?

The while loop evaluates the condition.
If the condition is true (nonzero), codes inside the body of while loop is executed. The condition is evaluated again. The process goes on until the condition is false.
When the condition is false, the while loop is terminated.

Example :

//program to print numbers from 1 to 10 in ascending order

#include<stdio.h>

void main(){

int i=1;

while(i<=10){

printf(“%d\t”,i);

i++;

}

(3).do while loop

The do..while loop is similar to the while loop with one important difference. The body of do...while loop is executed once, before checking the test expression. Hence, the do...while loop is executed at least once.

Syntax:

initialization;

do{

//loop body

updateExpression;

}while(testExpression);

How do...while loop works?

The code block (loop body) inside the braces is executed once.
Then, the testExpression is evaluated. If the testExpression is true, the loop body is executed again. This process goes on until the testExpression is evaluated to 0 (false).
When the testExpression is false (nonzero), the do...while loop is terminated.

Example:

//program to print numbers from 1 to 10.

#include<stdio.h>

void main(){

int i=1;

do{

printf(“%d\t”,i);

i++;

}while(i<=10);

}

Above discussed loops can be categorized into two groups based on-when test condition is tested.

(1). Entry controlled loop

The types of loop where the test condition is stated before the body of the loop, are known as the entry controlled loop.
In this category of loops, test condition is evaluated before entering into the loop body.
Example- for loop and while loop.

(2). Exit controlled loop

The types of loop where the test condition is stated at the end of the body of the loop, are known as the exit controlled loops.
So, in the case of the exit controlled loops, the body of the loop gets execution without testing the given condition for the first time.
Then the condition is tested. If it comes true, then the loop gets another execution and continues till the result of the test condition is not false.
Example : do while loop

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How to Create a User and Grant Permissions in Oracle

2019-03-28T16:09:00.001+05:30

Oracle comes with in-built database user like system and sys. But situation may arise where you want to create a separate user. You may want to create application specific users which may not need all privileges system and sys users have.

Step 1: Connect to oracle using system user with sysdba privilege.

SQLPLUS SYSTEM/password@sid AS SYSDBA;

Step 2 : Once your are connected to oracle, issue following command to create user

CREATE USER username IDENTIFIED BY password;

Replace username and password with your desired username and password.

Step 3: Once you have created user successfully, it may require certain permissions to do its job. You use GRANT statement to assign privileges.

Grant connect to test;

Grant resource to test;

Grant dba to test;

Grant create session to test;

Grant unlimited tablespace to tset;

Grant create view to test;

Grant create table to test;

Grant select on tableName to test;

Grant update on tableName to test;

Grant insert on tableName to test;

Grant delete on tableName to test;

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Switch Statement in C

2019-03-27T11:09:00.000+05:30

Switch case statements are a substitute for long if statements that compare a variable to several integral values. A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each switch case.

Syntax:

switch(expression){

case value1 : // code to be executed if expression = value1;

statement 1;

……………

………………

Break;//optional

case value2 : // code to be executed if expression = value2;

statement 1;

……………

………………

Break;//optional

case value3 : //// code to be executed if expression = value3;

statement 1;

……………

………………

Break;//optional

case value4 : // code to be executed if expression = value4;

statement 1;

……………

………………

Break;//optional

case value5 : // code to be executed if expression = value5;

statement 1;

……………

………………

Break;//optional

case valueN : //// code to be executed if expression = valueN;

statement 1;

……………

………………

Break;//optional

Default : // code to be executed if value of expression doesn't match any cases

Statement1;

………………………

}

Important Points about Switch Case Statements:

The expression provided in the switch should result in a constant value otherwise it would not be valid.
Duplicate case values are not allowed.
The default statement is optional.
The break statement is used inside the switch to terminate a statement sequence. When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.
The break statement is optional. If omitted, execution will continue on into the next case. The flow of control will fall through to subsequent cases until a break is reached.
The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.
When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.

Example:

//program to create simple calculator

#include<stdio.h>

int main(){

int num1,num2,result;

char operator;

printf("Enter operator(+,-,*,/,%):\n");

scanf("%c",&operator);

printf("Enter two positive integers:\n");

scanf("%d %d",&num1,&num2);

switch(operator){

case '+' :

result=num1+num2;

break;

case '-' :

result=num1-num2;

break;

case '*' :

result=num1*num2;

break;

case '/' :

result=num1/num2;

break;

case '%' :

result=num1%num2;

break;

default :

printf("Invalid operator!");

}

printf("Result of %c on %d and %d is %d.\n",operator,num1,num2,result);

return 0;

}

Output:

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C Program to Check Whether a Character is Vowel or Consonant

2019-03-26T16:52:00.000+05:30

This program demonstrates the functioning of if else statements. Program asks user for an alphabet and gives the output whether alphabet is vowel or consonant.

The five alphabets A, E, I, O and U are called vowels. All other alphabets except these 5 vowel letters are called consonants.

//C Program to Check Whether a alphabet is Vowel or Consonant

#include <stdio.h>

int main()

{

char ch;

printf("Enter an alphabet: ");

scanf("%c",&ch);

if((ch=='a' || ch=='A') || (ch=='e' || ch=='E') || (ch=='i' || ch=='I') || (ch=='o' || ch=='O') || (ch=='u' || ch=='U'))

printf("%c is a vowel.\n", ch);

else

printf("%c is a consonant.\n", ch);

return 0;

}

Output:

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C Program to check whether a number is even or odd

2019-03-26T15:00:00.000+05:30

This program demonstrates the functioning of if else statements. Program asks user for an integer number and gives the output whether number is even or odd.

An integer is even if it is divisible by 2 meaning if by dividing number by 2, remainder is zero, then number is even otherwise it is an odd number.

//C Program to demonstrate the functioning of if else statements

//check if number is divisible by 2. If it is, then number is even otherwise it is odd number

#include <stdio.h>

int main()

{

int num;

printf("Enter an integer: ");

scanf("%d", &num);

if(num % 2 == 0)

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

else

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

return 0;

}

Output:

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Decision making in C (If else,nested if)

2019-03-26T10:13:00.001+05:30

There comes situation when we need to make some decisions based on certain conditions and based on these decision we will perform a particular job.

Decision making statements in programming languages decides the direction of flow of program execution.

Following decision making constructs are available in C:

1. If statements

2. If Else statements

3. Switch Case

In this article, you will learn about if statements, if else statements and nested ifs.

1. if statement

if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.

Syntax:

if(condition){

//body of if ; it will be executed if condition in true

}

Example:

#include<stdio.h>

int main(){

int num=100;

if(num<150){

printf(“%d is smaller than 150.”);

}

return 0;

}

2.if else statement

The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
Syntax:

if(condition){

//body of if; it will be executed when condition is true

}

else{

//body of else; it will be executed only when condition is false

}

Example:

//Program to check whether an integer is positive or negative

#include<stdio.h>

int main(){

int num;

printf(“Enter an integer value except 0”);

scanf(“%d”,&num);

if(num>0){

printf(“%d is a positive integer.”);

}

else{

printf(“%d is a negative integer.”);

}

return 0;

}

If else ..if else..else statement(if else ladder)

When you have multiple options to check, if else ladder comes into picture.

The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.

Syntax:

if(condition 1){

}

else if(condition 2){

}

else if(condition 3){

}

else if(condition n){

}

else{

}

Example:

#include<stdio.h>

int main()

{

int num = 14;

if (num == 10)

printf(“%d is equal to 10”,num);

else if (num == 14)

printf(“%d is equal to 10”,num);

else if (num == 20)

printf(“%d is equal to 10”,num);

else

printf(“%d is not present",num);

return 0;

}

Nested if statements

Nested if statements means an if statement inside another if statement.

Syntax:

if(condition 1){

if(condition 2){

}

else{

}

else{

}

Example

//Program to find smaller number between two numbers

#include<stdio.h>

int main(){

int num1,num2;

printf(“Enter two integer numbers\n”);

scanf(“%d %d”,&num1,&num2);

if(num1!=num2){

if(num1<num2)

printf(“%d is smaller than %d.”,num1,num2);

else

printf(“%d is smaller than %d.”,num2,num1);

}

else

printf(“Both numbers are equal”);

return 0;

}

Please comment if you find anything incorrect, or you want to improve the topic discussed above