Pointer in C
#A pointer is a variable which contains or hold the address of another variable. We can create pointer variable of any type of variable for example integer type pointer is 'int *ptr'.
In pointer following symbols are use;
| Symbol | Nme | Description |
|---|---|---|
| & (ampersand sign) | Address of operator | Give the address of a variable |
| * (asterisk sign) | Indirection operator | Gives the contents of an object pointed to by a pointer. |
Advantage of pointer
- Pointer reduces the code and improves the performance, because it direct access the address of variable.
- Using pointer concept we can return multiple value from any function.
- Using pointer we can access any memory location from pointer.
Address Of Operator
The address of operator & gives the address of a variable. For display address of variable, we need %u.
Example
#include<stdio.h> void main() { int a=50; printf("\nValue of a is: %d",n); printf("\Address of &n is: %u",&n); }
Output
Value of a is: 50 Address of a is: 1002
Declaring a pointer
In C language for declared pointer we can use * (asterisk symbol).
Syntax
int *p; //pointer to integer char *ch; //pointer to character
Example of pointer
In below image pointer variable stores the address of num variable i.e. EEE3. The value of num is 50 and address of pointer prt is CCC4
Example
#include<stdio.h> int main () { int num=50; int *ptr; // pointer variable ptr = # // store address of variable in pointer printf("Address of num variable: %x\n", &num); /* address stored in pointer variable */ printf("Address stored in ptr variable: %x\n", ptr ); /* access the value using the pointer */ printf("Value of *ptr variable: %d\n", *ptr ); return 0; }
Output
Address of num variable: EEE3 Address stored in ptr variable: CCC4 Value of *ptr variable: 50
NULL Pointer
A pointer that is not assigned any value but NULL is known as NULL pointer. This is done at the time of variable declaration. The NULL pointer is a constant which is defined in standard libraries with zero value.
Example
#include<stdio.h> int main () { int *ptr = NULL; printf("Value of ptr is: %x", ptr ); return 0; }
Output
Value of ptr is: 0
