Pointer arithmetic is a powerful concept in C programming, enabling manipulation of memory addresses rather than just data values. This blog delves into the operations that can be performed on pointers, including incrementing, decrementing, adding, and subtracting integers to pointers, as well as subtracting and comparing pointers of the same type. Learn how pointer arithmetic simplifies memory navigation, enhances code efficiency, and unlocks advanced programming techniques. With examples and clear explanations, you’ll grasp how operations like ptr++, ptr--, and pointer comparisons work in real-world scenarios.
Unlike regular variables, pointer variables do not store actual values; instead, they hold the memory addresses of other variables. Due to this, the arithmetic operations that can be performed on pointers are limited and differ from standard mathematical operations.
Increment/Decrement of a Pointer
Addition of integer to a pointer
Subtraction of integer to a pointer
Subtracting two pointers of the same type
Comparison of pointers
increment/decrement of a pointer:
int *ptr;
Ptr++;
Ptr–;
If the base address is 5000
Ptr++=5000+4;
Ptr–=5000-4;
For example if the base address is 5000 the ptr++=5004
And ptr–=5000-4=996;
Addition of integer to a pointer:
#include <stdio.h>
int main()
{
int a=22;
char b=’a’;
int c[]={1,2,3,4,5};
float d=12.22;
int *p=&a;
char *q=&b;
int *r=&c;
printf(“%d integer ptr increment”,p++);
printf(“%d integer ptr decrement “,p–);
printf(“%d char ptr increment”,q++);
printf(“%d char ptr decrement”,q–);
printf(“%d array pointer increment “, r++);
printf(“%d array pointer decrement”,r–);
printf(“%dfloat pointer increment”,d++);
printf(“%dfloat pointer decrement”,d–);
}
Addition of integer to a pointer:
// C program to illustrate pointer Addition
#include <stdio.h>
// Driver Code
int main()
{
// Integer variable
int p= 4;
// Pointer to an integer
int *p1, *p2;
//
p1 = &N;
p2 = &N;
printf(“Pointer ptr2 before Addition: “);
printf(“%p \n”, p1);
// Addition of 3 to ptr2
p2 = p2 + 3;
printf(“Pointer ptr2 after Addition: “);
printf(“%p \n”, p2);
return 0;
}
#include <stdio.h>
// Driver Code
int main()
{
// Integer variable
int p= 4;
// Pointer to an integer
int *p1, *p2;
//
p1 = &p;
p2 = &p;
printf(“Pointer ptr2 before Addition: “);
printf(“%p \n”, p1);
// Addition of 3 to ptr2
p2 = p2 – 3;
printf(“Pointer ptr2 after subtraction: “);
printf(“%p \n”, p2);
return 0;
}
Subtraction of two pointers:
// C program to illustrate Subtraction
// of two pointers
#include <stdio.h>
// Driver Code
int main()
{
int x =6;
int N = 4;
// Pointer declaration
int *p1, *p2;
p1 = &N;
p2 = &x;
// %p gives an hexa-decimal value,
// Subtraction of ptr2 and ptr1
x = p1 – p2;
// between ptr1 and ptr2
printf(“Subtraction of p1 “
“& p2 is %d\n”,
x);
return 0;
}
-We can compare the two pointers
-with the comparison operators.
< ,>,<=,>=
// C Program to illustrare pointer comparision
#include <stdio.h>
int main()
{
// declaring array
int a[5];
// declaring pointer to array name
int* p1 = &a;
// declaring pointer to first element
int*p2 = &a[0];
if (p1 == p2) {
printf(“
Equal.”);
}
else {
printf(“
“are not Equal.”);
}
return 0;
}