Pointer Vs Array in C

Pointers and arrays are closely related in C, and in many expressions an array name behaves like a pointer to its first element. However, they are not the same, and they differ in memory allocation, assignment, arithmetic, and several other operations.

• An array is a fixed-size collection of elements stored in contiguous memory locations, whereas a pointer is a variable that stores the address of another variable.
• Although array names often decay into pointers, arrays and pointers behave differently with operators like sizeof, &, assignment, and pointer arithmetic.

#include <stdio.h>

int main() {
    int array[5] = {10, 20, 30, 40, 50};
    int *pointer = array;

    printf("First array element = %d\n", array[0]);
    printf("First element using pointer = %d\n", *pointer);

    printf("Size of array = %zu bytes\n", sizeof(array));
    printf("Size of pointer = %zu bytes\n", sizeof(pointer));

    pointer++;          // Valid
    printf("Pointer now points to = %d\n", *pointer);

    // array++;         // Invalid: Array name cannot be modified

    return 0;
}

First array element = 10
First element using pointer = 10
Size of array = 20 bytes
Size of pointer = 8 bytes
Pointer now points to = 20

Explanation

• An array stores a fixed collection of elements, whereas a pointer stores the memory address of another variable.
• Arrays have fixed memory and cannot be reassigned, while pointers can point to different memory locations and support pointer arithmetic.
• Although array names often behave like pointers, they differ in operations such as sizeof, assignment, and increment (++).

Difference Between Pointer and Array