1. Static Assignment

You can directly assign values at the time of declaration.

#include < stdio.h>

int main() {
    // Declare and initialize an array
    int arr[5] = {10, 20, 30, 40, 50};

    // Print values
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
    return 0;
}

            

2. Dynamic Assignment

You can assign values to specific elements after declaring the array.

#include < stdio.h>

int main() {
    int arr[5]; // Declare an array

    // Assign values to the array
    arr[0] = 5;
    arr[1] = 10;
    arr[2] = 15;
    arr[3] = 20;
    arr[4] = 25;

    // Print values
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
    return 0;
}

            

3. User Input to Array

You can take input from the user and assign values to an array.

#include < stdio.h>

int main() {
    int arr[5]; // Declare an array

    // Input values from the user
    printf("Enter 5 numbers:\n");
    for (int i = 0; i < 5; i++) {
        printf("Enter value for arr[%d]: ", i);
        scanf("%d", &arr[i]); // Assign values based on user input
    }

    // Print the values
    printf("\nThe values in the array are:\n");
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }

    return 0;
}

            

4. Partially Initialized Arrays

If you initialize only some elements, the rest will automatically be set to 0.

#include < stdio.h>

int main() {
    int arr[5] = {1, 2}; // Only the first two elements are initialized

    // Print values to check
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
    return 0;
}

            

Key Points to Remember

• Indexing starts at 0: The first element is arr[0], the second is arr[1], and so on.
• Array size must be specified: When declaring an array without initializing it, you need to provide its size (e.g., int arr[10];).
• Out-of-bounds access: Accessing or modifying indices outside the array's declared size leads to undefined behavior.