How to Access Array Elements Using Pointer in C

In C, you can access array elements using a pointer by pointing to the array's first element and then using pointer arithmetic like *(ptr + index) to get each element. The pointer moves through the array by adding the index to it, which accesses elements sequentially.

Syntax

To access array elements using a pointer, you first assign the pointer to the array's first element. Then use *(pointer + index) to get the element at the given index.

• pointer: a variable holding the address of the array's first element.
• index: the position of the element you want to access (starting from 0).
• *(pointer + index): dereferences the pointer at the offset index to get the element.

c

int arr[] = {10, 20, 30};
int *ptr = arr; // pointer to first element
int value = *(ptr + 1); // accesses arr[1], which is 20

Example

This example shows how to use a pointer to access and print all elements of an integer array.

c

#include <stdio.h>

int main() {
    int arr[] = {5, 10, 15, 20, 25};
    int *ptr = arr; // pointer to first element
    int length = sizeof(arr) / sizeof(arr[0]);

    for (int i = 0; i < length; i++) {
        // Access element using pointer arithmetic
        printf("Element %d: %d\n", i, *(ptr + i));
    }

    return 0;
}

Output

Element 0: 5
Element 1: 10
Element 2: 15
Element 3: 20
Element 4: 25

Common Pitfalls

Common mistakes when accessing array elements using pointers include:

• Not initializing the pointer to the array's first element before using it.
• Accessing out-of-bounds elements by using an index outside the array size, which causes undefined behavior.
• Confusing ptr[index] and *(ptr + index) — both work the same, but forgetting the dereference operator * leads to errors.

c

/* Wrong: pointer not initialized */
int *ptr;
// printf("%d", *ptr); // Undefined behavior

/* Right: pointer initialized to array */
int arr[] = {1, 2, 3};
int *ptr = arr;
printf("%d", *(ptr + 1)); // Prints 2

Output

2

Quick Reference

Concept	Description	Example
Pointer to array	Points to the first element of the array	int *ptr = arr;
Access element	Use pointer arithmetic and dereference	*(ptr + i) or ptr[i]
Pointer arithmetic	Moves pointer by element size	ptr + 1 points to next element
Array name	Acts as pointer to first element	arr == &arr[0]

Key Takeaways

Use a pointer initialized to the array's first element to access elements.

Access elements with pointer arithmetic: *(ptr + index) or ptr[index].

Avoid accessing elements outside the array bounds to prevent errors.

Array name can be used as a pointer to the first element.

Always ensure the pointer is properly initialized before dereferencing.