Accessing array elements using pointer

Use of pointers in C

A pointer is a variable holding the address of another variable. It is used for call by reference, dynamic memory allocation (malloc), efficient array and string handling, and building data structures such as linked lists and trees.

Accessing array elements with a pointer

The array name is the address of its first element, so a pointer can be set to it: int *p = a;. Then:

• *p is a[0], *(p + 1) is a[1], and in general *(p + i) is a[i].
• The pointer can be moved with p++ to visit the next element.

#include <stdio.h>

int main(void)
{
    int a[5] = {5, 10, 15, 20, 25}, *p = a, sum = 0;

    for (int i = 0; i < 5; i++)
        printf("a[%d] = %d\n", i, *(p + i));    /* value using pointer */

    for (p = a; p < a + 5; p++)                 /* moving the pointer */
        sum += *p;
    printf("Sum = %d\n", sum);
    return 0;
}

Output:

a[0] = 5
a[1] = 10
a[2] = 15
a[3] = 20
a[4] = 25
Sum = 75