Pointer Arithmetic in C

January 17, 2023

Pointer Arithmetic :

Pointer Arithmetic In C is defined as the arithmetic operation can be performed on pointers as pointers are address of data type which is value.

Arithmetic on Pointers :

We can perform following arithmetic operation on Pointers:

Increment/Decrement of a Pointer.
Addition/Subtraction of Integer to a Pointer.
Subtracting of two Pointer of similar type.
Comparison of two Pointer of similar type.

Increment/Decrement of a Pointer :

When a pointer is incremented/decremented , it will incremented/decremented by a number equal to the size of data type for which it is a pointer.

Example :

In the below program, we are explaining the incrementing or decrementing on a pointer.

Run

#include<stdio.h>
int main() {
    
    int val = 10;
    int *ptr = &val;
    
    printf("The value of adress of pointer : %u\n", ptr);
    
    ptr++;
    printf("The value of address of pointer after incrementing : %u\n", ptr);
    
     ptr--;
     printf("The value of address of pointer after decrementing : %u", ptr);

    return 0;
}

Output :

The value of adress of pointer : 2221651772
The value of address of pointer after incrementing : 2221651776
The value of address of pointer after decrementing : 2221651772

What Exactly Happened Above?

Explanation The address value of pointer is 2221651772(depends on compiler) , after incrementing it is incremented by 4 as it is a pointer of int data type which size is 4.

Pointers in C

Access array using pointer

Null pointer

Function pointer

Pointer v/s array

Addition/Subtraction of Integer to a Pointer :

When a pointer is added/subtracted by a value , it first multiplied by size of data type and then added/subtracted to a pointer

Example :

In the below program, we are explaining the addition/subtraction of integer on a pointer.

Run

#include<stdio.h>#include

int main()
{
	int val = 9;
	int *ptr = &val;
	
	printf("Value of Pointer before Addition : ");
	printf("%p \n", ptr);

	ptr = ptr + 5;
	printf("Pointer ptr after Addition: ");
	printf("%p \n", ptr);

	return 0;
}

Output :

Value of Pointer before Addition : 0x7ffe75b09ffc
Pointer ptr after Addition: 0x7ffe75b0a010

Subtracting of two pointers of similar type :

Subtraction of two pointers is only possible, if they have same data type. When two pointers of same data type is subtracted , their value is subtracted then result will be divided by the size of data type.

Example :

In the below program, we explain the subtraction of two pointers of similar data type.

Run

#include<stdio.h>
int main()
{
	int val1 = 8, val2 = 6;

	int *ptr1, *ptr2;
        ptr1 = &val1; 
	ptr2 = &val2; 

	printf("Value of  adress of ptr1 = %u \n", ptr1);
	printf("Value of address of ptr2 = %u \n", ptr2);

	val1 = ptr2 - ptr1;
	printf("Subtraction is %d\n",	val1);

	return 0;
}

Output :

Value of  adress of ptr1 = 2406668336 
Value of address of ptr2 = 2406668340 
Subtraction is 1

Comparison of two pointers of similar type :

Comparison of two pointers is only possible, if they have same data type. Two pointers can be compared by the operators >, ==, <= , >=. It returns TRUE if condition valid, otherwise return FALSE.

Example :

In the below program, we explain the comparison of two pointers of similar data type.

Run

#include<stdio.h>#include

int main() {

	int val1 = 10, val2 = 5; 
	int *ptr1=&val1;
	int *ptr2=&val2;
	
	
if(*ptr1<*ptr2)
{
	printf("\n%d less than %d",*ptr2,*ptr1);
}
else if(*ptr2<*ptr1)
{
	printf("\n%d greater than %d",*ptr1,*ptr2);
}
else{
    printf("Both values are equal");
}


	return 0;
}

Output :

10 greater than 5

Prime Course Trailer

Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

Get over 200+ course One Subscription

Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others

Pointer Arithmetic in C