In C, an array is a collection of elements of the same data type, stored in contiguous memory locations. It provides a way to store multiple values of the same data type under a single variable name. The elements in an array can be accessed using their index, which starts from 0 and goes up to the array size minus one.

Usage and Syntax:

To declare an array in C, you specify the data type of the elements followedby the array name and the size of the array in square brackets.

data_type array_name[size];

Sample Code with Explanation and Output:

#include <stdio.h>

int main() {
    // Declaration and initialization of an integer array
    int numbers[5] = {10, 20, 30, 40, 50};

    // Accessing array elements using index
    printf("Array Elements: ");
    for (int i = 0; i < 5; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");

    // Modifying array elements
    numbers[2] = 35; // Change the value at index 2 to 35

    // Accessing and printing the modified array
    printf("Modified Array: ");
    for (int i = 0; i < 5; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");

    // Calculate the sum of all elements in the array
    int sum = 0;
    for (int i = 0; i < 5; i++) {
        sum += numbers[i];
    }
    printf("Sum of array elements: %d\n", sum);

    return 0;
}

Output:

Array Elements: 10 20 30 40 50
Modified Array: 10 20 35 40 50
Sum of array elements: 155

Explanation:

• In the sample code, declare an integer array numbers of size 5 and initialize it with values {10, 20, 30, 40, 50}.
• Use a for loop to access and print the array elements using their indices.
• After that, modify the value at index 2 to 35 (changing 30 to 35).
• Next, access and print the modified array.
• Finally, calculate the sum of all elements in the array using a loop and print the sum.