POINTERS IN C LANGUAGE

File pointer in c

2012-01-28T10:42:00.000+05:30

What is file pointer in c programming language?

FILE pointer is struct data type which has been defined in standard library stdio.h. This data type points to a stream or a null value. It has been defined in stdio.h as

typedef struct{

short level;

unsigned flags;

char fd;

unsigned char hold;

short bsize;

unsigned char *buffer, *curp;

unsigned istemp;

short token;

} FILE;

Examples:

To get the examples go through the following link:

File handling tutorials

If you have any quires in file pointers, you can ask here.

What is pointer in c programming?

2011-11-30T01:24:00.000+05:30

Explain pointers in c

Pointer is a user defined data type which creates special types of variables which can hold the address of primitive data type like char, int, float, double or user defined data type like function, pointer etc. or derived data type like array, structure, union, enum.

Examples:

int *ptr;

int (*ptr)();

int (*ptr)[2];

In c programming every variable keeps two type of value.

1. Contain of variable or value of variable.

2. Address of variable where it has stored in the memory.

(1) Meaning of following simple pointer declaration and definition:

int a=5;

int * ptr;

ptr=&a;

Explanation:

About variable a:

1. Name of variable : a

2. Value of variable which it keeps: 5

3. Address where it has stored in memory : 1025 (assume)

About variable ptr:

4. Name of variable : ptr

5. Value of variable which it keeps: 1025

6. Address where it has stored in memory : 5000 (assume)

Pictorial representation:

Note: A variable where it will be stored in memory is decided by operating system. We cannot guess at which location a particular variable will be stored in memory.

(2) Meaning of following pointer declaration and definition:

int a=50;

int *ptr1;

int **ptr2;

ptr1=&a;

ptr2=&pt1;

Explanation:

About variable a:

1. Name of variable : a

2. Value of variable which it keeps: 50

3. Address where it has stored in memory : 5000 (assume)

About variable ptr1:

4. Name of variable : ptr1

5. Value of variable which it keeps: 5000

6. Address where it has stored in memory : 9000 (assume)

About variable ptr2:

7. Name of variable : ptr2

8. Value of variable which it keeps: 9000

9. Address where it has stored in memory : 9555 (assume)

Pictorial representation of above pointer declaration and definition:

Note:

* is known as indirection operator which gives content of any variable.

& is known as reference operator which gives address where variable has stored in memory.

Cancellation rule of above two operators:

* and & operators always cancel to each other i.e.

*&p=p

But it is not right to write:

&*p=p

Simple example:

What will be output of following c program?

#include<stdio.h>

int main(){

int x=25;

int *ptr=&x; //statement one

int **temp=&ptr; //statement two

printf(“%d %d %d”.x.*ptr,**temp);
return 0;

}

Output: 25 25 25

Explanation:

As we know value of variable x is 25.

*ptr= *(&x) //from statement one

=*&x

=x //using cancellation rule

=25

**temp= **(&ptr)=*(*&ptr)=*ptr=*(&x)=*&x=x=25

Definition of pointer
How to read complex pointer
Arithmetic operation with pointer
Pointer to function
Pointer to array of function
Pointer to array of string
Pointer to structure
pointer to union
Multi level pointer
Pointer to array of pointer to string
Pointer to three dimentional array
Pointer to two dimensional array
Sorting of array using pointer
Pointer to array of array
Pointer to array of union
Pointer to array of structure
Pointer to array of character
Pointer to array of integer
Complex pointer
Generic pointer
Null pointer
Wild pointer
Dangling pointer
Near pointer
Far pointer
Graphics video memory
Text video memory
Huge pointer
Memory model in C
C tutorial

C with pointers

2011-11-29T01:53:00.000+05:30

Factorial program in c using pointers

CONCATENATION OF TWO STRINGS USING POINTER IN C PROGRAM

Accessing 2d array using pointers

Bubble sort in c using pointers

Binary search using pointers in c

C program to reverse a string using pointers

Matrix multiplication in c using pointers programming

Reverse a string in c using pointers

Swap two numbers using pointers

Advantages and disadvantages of using pointers

Accessing array elements using pointers in c

C program for stack using pointers

Write a program to find substring using pointers

Find the smallest number in an array using pointers

Linked list program in c using pointers

Reversing a linked list using 2 pointers

Addition of two matrixes in c using pointers

Queue program in c using pointers

String copy using pointers

Pointers to pointers in c

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C pointers to pointers: A pointer is pointer to another pointer which can be pointer to others pointers and so on is known as multilevel pointers or pointer to pointers. We can have any level of pointers.

Examples of pointers to pointers in c:

(1) What will be output if you will execute 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

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

#include<stdio.h>

#define int int*

int main(){

int *p,q;

p=(int *)5;

q=10;

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

return 0;

}

Output: 25

Explanation: If you will see intermediate file you will find following code:

#include<stdio.h>

void main(){

int **p,q;

p=(int **)5;

q=10;

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

return 0;

}

Explanations:

Here q pointer and p is a number.

In c

Address + number = Address

So,

New address = old address + number * Size of data type to which pointer is pointing.

= 5 + 10 * sizeof (*int)

= 5+10*2 = 25.

Note. We are assuming default pointer is near. Actually it depends upon memory model.

Pointers tutorial in c pdf

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C programming pointers and arrays

2011-11-28T02:32:00.002+05:30

Pointers and arrays in c programming

Array tutorial in c programming language by examples

An array is derived data type in c programming language which can store similar type of data in continuous memory location. Data may be primitive type (int, char, float, double…), address of 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) We have to store large number of data of similar type. If we have large number of similar kind of variable then it is very difficult to remember name of all variables and write the program. For example:

//PROCESS ONE
#include<stdio.h>

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
#include<stdio.h>

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) We want to store large number of data in continuous memory location. Array always stores data in continuous memory location.

(q) What will be output when you will execute the following program?

#include<stdio.h>

int main(){

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

char *ptr=arr;

arr=arr+2;

printf("%d",*arr);
return 0;

}

Advantage of using array:

1. An array provides singe name .So it easy to remember the name of all element of an array.

2. Array name gives base address of an array .So with the help increment operator we can visit one by one all the element of an array.

3. Array has many application data structure.

Array of pointers in c:
Array whose content is address of another variable is known as array pointers. For example:

#include<stdio.h>

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;

}

Complex arrays in c

1. Declaration of an array of size five which can store address such functions whose parameter is void data type and return type is also void data type:

void ( arr[5] )( );

2. Declaration of an array of size five which can store address such function which has two parameter of int data type and return type is float data type:

float ( arr[5] )(int, int);

3. Declaration of an array of size two which can store the address of printf or sacanf function:

int ( arr[2] )( const char *, … );

Note: prototype of printf function is: int printf( const char *, … );

Different type of array in c:

(a) Array of integer

An array which can hold integer data type is known as array of integer.

(b) Array of character

An array which can hold character data type is known as array of character.

An array which can hold address of union data type is known as union of integer.

For example:

(1) What will be output when you will execute the following program?

#include<stdio.h>

union A{

char p;

float const * const q;

};

int main(){

union A arr[10];

printf("%d",sizeof arr);
return 0;
}

Output: 20

(2) What will be output when you will execute the following program?

#include<stdio.h>
union A{

char character;

int ascii;

};

int main(){

union A arr[2]={{65},{'a'}};

printf("%c %c",arr[0],arr[1]);
return 0;

}

Output: A a

(d) Array of structure

An array which can hold address of structure data type is known as array of structure. For example:

(1) What will be output when you will execute the following program?

#include<stdio.h>

typedef struct stu{

char * name;

int roll;

}s;

int main(){

s arr[2]={{"raja",10},{"rani",11}};

printf("%s %d",arr[0]);

return 0;
}

Output: raja 10

(2) What will be output when you will execute the following program?

#include<stdio.h>

struct A{

int p;

float q;

long double *r;

};

int main(){

struct A arr[10];

printf("%d",sizeof arr);

return 0;
}

Output: 80

(e) Array of string

An array which can hold integer data type is known as array of integer.

(f) Array of array

An array which can hold address of another array is known as array of array.

(g) Array of address of integer

An array which can hold address integer data type is known as array of address of integer.

Pointer to array

A pointer which holds base address of an array or address of any element of an array is known as pointer to array. For example:

(a)

#include<stdio.h>

int main(){

int arr[5]={100,200,300};

int *ptr1=arr;

char *ptr2=(char *)arr;

printf("%d %d",*(ptr1+2),*(ptr2+4));

return 0;

}

Output: 300 44

(b)

#include<stdio.h>

int main(){

static int a=11,b=22,c=33;

int * arr[5]={&a,&b,&c};

int const * const *ptr=&arr[1];

--ptr;

printf("%d ",**ptr);
return 0;

}

Output: 11

Pointers tutorial in c programming language by examples

Examples:

int *ptr;

int (*ptr)();

int (*ptr)[2];

In c programming every variable keeps two type of value.

1. Contain of variable or value of variable.

2. Address of variable where it has stored in the memory.

(1) Meaning of following simple pointer declaration and definition:

int a=5;

int * ptr;

ptr=&a;

Explanation:

About variable a:

1. Name of variable : a

2. Value of variable which it keeps: 5

3. Address where it has stored in memory : 1025 (assume)

About variable ptr:

4. Name of variable : ptr

5. Value of variable which it keeps: 1025

6. Address where it has stored in memory : 5000 (assume)

Pictorial representation:

Note: A variable where it will be stored in memory is decided by operating system. We cannot guess at which location a particular variable will be stored in memory.

(2) Meaning of following pointer declaration and definition:

int a=50;

int *ptr1;

int **ptr2;

ptr1=&a;

ptr2=&pt1;

Explanation:

About variable a:

1. Name of variable : a

2. Value of variable which it keeps: 50

3. Address where it has stored in memory : 5000 (assume)

About variable ptr1:

4. Name of variable : ptr1

5. Value of variable which it keeps: 5000

6. Address where it has stored in memory : 9000 (assume)

About variable ptr2:

7. Name of variable : ptr2

8. Value of variable which it keeps: 9000

9. Address where it has stored in memory : 9555 (assume)

Pictorial representation of above pointer declaration and definition:

Note:

* is known as indirection operator which gives content of any variable.

& is known as reference operator which gives address where variable has stored in memory.

Cancellation rule of above two operators:

* and & operators always cancel to each other i.e.

*&p=p

But it is not right to write:

&*p=p

Simple example:

What will be output of following c program?

#include<stdio.h>

int main(){

int x=25;

int *ptr=&x; //statement one

int **temp=&ptr; //statement two

printf(“%d %d %d”.x.*ptr,**temp);
return 0;

}

Output: 25 25 25

Explanation:

As we know value of variable x is 25.

*ptr= *(&x) //from statement one

=*&x

=x //using cancellation rule

=25

**temp= **(&ptr)=*(*&ptr)=*ptr=*(&x)=*&x=x=25

Pointers in c ppt presentation

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C pointers quiz

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Data type questions

Variable naming rule questions

Operators questions

Control flow questions

Switch case questions

Looping questions

Mastering c pointers

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To be master in pointers you must know how to read any types of pointers in c.

Rule 1. Assign the priority to the pointer declaration considering precedence and associative according to following table.

Where

(): This operator behaves as bracket operator or function operator.

[]: This operator behaves as array subscription operator.

*: This operator behaves as pointer operator not as multiplication operator.

Identifier: It is not an operator but it is name of pointer variable. You will always find the first priority will be assigned to the name of pointer.

Data type: It is also not an operator. Data types also includes modifier (like signed int, long double etc.)

You will understand it better by examples:

(1) How to read following pointer?

char (* ptr)[3]

Answer:

Step 1: () and [] enjoys equal precedence. So rule of associative will decide the priority. Its associative is left to right So first priority goes to ().

Step 2: Inside the bracket * and ptr enjoy equal precedence. From rule of associative (right to left) first priority goes to ptr and second priority goes to *.

Step3: Assign third priority to [].

Step4: Since data type enjoys least priority so assign fourth priority to char.

Now read it following manner:

ptr is pointer to such one dimensional array of size three which content char type data.

(2) How to read following pointer?

float (* ptr)(int)

Answer:

Assign the priority considering precedence and associative.

Now read it following manner:

ptr is pointer to such function whose parameter is int type data and return type is float type data.

Rule 2: Assign the priority of each function parameter separately and read it also separately.

Understand it through following example.

(3) How to read following pointer?

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

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

ptr is pointer to such function which first parameter is pointer to one dimensional array of size two which content int 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 rule of precedence and associative.

Now read it following manner:

ptr is pointer to such array of size five which content are pointer to such function which parameter is void and return type is int type data.

(5) How to read following pointer?

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

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

ptr is pointer to function which parameter is int type data and return type is pointer to function which first parameter is pointer to pointer of double data type and second parameter is char type data type and return type is pointer to double data type.

(6) How to read following pointer?

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

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

ptr is pointer to array of size eight and content of array is pointer to function which first parameter is pointer to character constant and second parameter is variable number of arguments and return type is pointer to pointer of unsigned int data type.

C programming pointers tutorial

2011-11-27T20:34:00.000+05:30

Learning pointers in c

2011-11-27T20:31:00.002+05:30

Basics of pointers in c

To learn pointers in c you must have to understand basic of its. Pointer is a user defined data type which creates special types of variables which can hold the address of primitive data type like char, int, float, double or user defined data type like function, pointer etc. or derived data type like array, structure, union, enum.

Examples:

int *ptr;

int (*ptr)();

int (*ptr)[2];

In c programming every variable keeps two type of value.

1. Contain of variable or value of variable.

2. Address of variable where it has stored in the memory.

(1) Meaning of following simple pointer declaration and definition:

int a=5;

int * ptr;

ptr=&a;

Explanation:

About variable a:

1. Name of variable: a

2. Value of variable which it keeps: 5

3. Address where it has stored in memory: 1025 (assume)

About variable ptr:

4. Name of variable: ptr

5. Value of variable which it keeps: 1025

6. Address where it has stored in memory: 5000 (assume)

Pictorial representation:

Note: A variable where it will be stored in memory is decided by operating system. We cannot guess at which location a particular variable will be stored in memory.

(2) Meaning of following pointer declaration and definition:

int a=50;

int *ptr1;

int **ptr2;

ptr1=&a;

ptr2=&pt1;

Explanation:

About variable a:

1. Name of variable: a

2. Value of variable which it keeps: 50

3. Address where it has stored in memory: 5000 (assume)

About variable ptr1:

4. Name of variable: ptr1

5. Value of variable which it keeps: 5000

6. Address where it has stored in memory: 9000 (assume)

About variable ptr2:

7. Name of variable: ptr2

8. Value of variable which it keeps: 9000

9. Address where it has stored in memory: 9555 (assume)

Pictorial representation of above pointer declaration and definition:

Note:

* is known as indirection operator which gives content of any variable.

& is known as reference operator which gives address where variable has stored in memory.

Cancellation rule of above two operators:

* and & operators always cancel to each other i.e.

*&p=p

But it is not right to write:

&*p=p

Simple example:

What will be output of following c program?

#include<stdio.h>

int main(){

int x=25;

int *ptr=&x; //statement one

int **temp=&ptr; //statement two

printf(“%d %d %d”.x.*ptr,**temp);

return 0;

}

Output: 25 25 25

Explanation:

As we know value of variable x is 25.

*ptr= *(&x) //from statement one

=*&x

=x //using cancellation rule

=25

**temp= **(&ptr)=*(*&ptr)=*ptr=*(&x)=*&x=x=25

Incrementing pointers in c

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Address + Number= Address

Address - Number= Address

Address++ = Address

Address-- = Address

++Address = Address

--Address = Address

If we will increment or decrement a pointer result will be an address which and new address can be calculated by following formula:

Examples:

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

#include<stdio.h>

int main(){

int *ptr=( int *)1000;

ptr=ptr+1;

printf(" %u",ptr);

return 0;

}

Output: 1002

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

#include<stdio.h>

int main(){

double *p=(double *)1000;

p=p+3;

printf(" %u",p);

return 0;

}

Output: 1024

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

#include<stdio.h>

int main(){

float array[5]={1.1f,2.2f,3.3f};

float(*ptr)[5];

ptr=&array;

printf("%u",ptr);

ptr=ptr+1;

printf(" %u",ptr);

return 0;

}

Output: 1000 1020

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

#include<stdio.h>

typedef struct abc{

int far*a;

double b;

unsigned char c;

}ABC;

int main(){

ABC *ptr=(ABC *)1000;

ptr=ptr+2;

printf(" %u",ptr);

return 0;

}

Output: 1026

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

#include<stdio.h>

typedef union abc{

char near*a;

long double d;

unsigned int i;

}ABC;

int main(){

ABC *ptr=(ABC *)1000;

ptr=ptr-4;

printf(" %u",ptr);

return 0;

}

Output: 960

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

#include<stdio.h>

float * display(int,int);

int max=5;

int main(){

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

ptr=display;

(*ptr)(2,2);

printf("%u",ptr);

ptr=ptr+1;

printf(" %u",ptr);

return 0;

}

float * display(int x,int y){

float f;

f=x+y+max;

return &f;

}

Output: Compiler error

Different types of pointers in c

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There any many types of pointers according to behaviors. They are:

Near pointer in C programming

Far pointer in c programming

Huge pointer in c programming

Complex pointers in c pdf

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Pointers arithmetic in c programming pdf

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Functions and pointers in c pdf

2011-08-24T19:52:00.006+05:30

Pointers and arrays in c pdf

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Pointers in c programming pdf

2011-08-24T09:26:00.023+05:30

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(A)	ptr is pointer to function.
(B)	ptr is array of pointer to function.
(C)	ptr is pointer to such function which return type is array.
(D)	ptr is pointer to array of function.
(E)	None of these

(A)	ptr is pointer to function.
(B)	ptr is array of pointer to function.
(C)	ptr is pointer to such function which return type is pointer to an array.
(D)	ptr is pointer array of function.
(E)	None of these

(A)	0
(B)	1
(C)	2
(D)	Null
(E)	Undefined

(A)	1 2 4 8
(B)	2 4 4 8
(C)	2 4 2 4
(D)	2 2 2 2
(E)	2 2 4 4

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

(A)	15 18 21
(B)	21 21 21
(C)	24 24 24
(D)	Compiler error
(E)	None of above

(A)	All are collect.
(B)	Only (ii) is incorrect.
(C)	Only (iv) is incorrect.
(D)	Both (iii) and (v) are incorrect.
(E)	All are incorrect.

(A)	C Question Bank
(B)	Question Bank
(C)	Bank
(D)	estion Bank
(E)	Compilation error

(A)	Near pointer.
(B)	Far pointer.
(C)	Huge pointer.
(D)	Near and far pointer.
(E)	Near,far and huge pointer.

(A)	C question Bank
(B)	C quesdion Bank
(C)	C qdestion Bank
(D)	C q100estion Bank
(E)	Compilation error

(A)	int(*ptr)()
(B)	long **volatile*ptr
(C)	int(*ptr[2])[3]
(D)	float * (*ptr)[5]
(E)	All are pointer

(A)	We can increment array pointer
(B)	We can increment function pointer
(C)	We can increment structure pointer
(D)	We can increment union pointer.
(E)	We can increment generic pointer.

(A)	Only (i) is incorrect.
(B)	Only (ii) is incorrect.
(C)	Only (iii) is incorrect.
(D)	Both (ii) and (iii) are incorrect.
(E)	All three are incorrect.