Arithmetic Operation With Pointer

In a C programming, we can also perform arithmetic operations with pointer.

There are four arithmetic operators that can be performed with pointers:

• Increment (++)
• Decrement ( — )
• Addition ( + )
• Subtraction ( – )

 For a simple variable
int a=3;
a++; //print 4
Increment integer value by one.

Pointer is a variable which can hold the address of another variable in above code

For pointer
int a=3;
int *ptr;
ptr=a;
ptr++; //increment by one integer address space

pointer variable address value are incremented based on type of values it holds

Increment a Pointer

Example: Write a program in c language, to increments the variable pointer to access each succeeding element of the array.

#include 
int main () 
{
   int  arr[] = {10, 20, 30};
   int  i, *ptr;

      ptr = arr;			//assign the stsrting array address to pointer variable pointer

for ( i = 0; i < 3; i++) 
{		
    printf("\n Address of arr[%d] = %d", i, ptr );
    printf("\n Value of arr[%d] = %d", i, *ptr );
    ptr++;	// move to the next location 
   	}
 return 0;
}

OUTPUT

 Address of arr[0] = -908782628
 Value of arr[0] = 10
 Address of arr[1] = -908782624
 Value of arr[1] = 20
 Address of arr[2] = -908782620
 Value of arr[2] = 30

In above program we can also decrements the pointer.

In above program you have to loop in decrement way as below

for ( i = 2; i >=0; i--) 
{		
     printf("\n Address of arr[%d] = %d", i, ptr );
     printf("\n Value of arr[%d] = %d", i, *ptr );
     ptr--;		// move to the previous location 
}

 Address of arr[2] = 857698604
 Value of arr[2] = 10
 Address of arr[1] = 857698600
 Value of arr[1] = -1252756080
 Address of arr[0] = 857698596
 Value of arr[0] = 32765