Delete an element from the array from user defined position.

Learn how to remove an element from any position in an array

array_deletion.c

#include <stdio.h>

int main() {
    int arr[20], n, i, pos;

    // Input current size of array
    printf("Enter number of elements (max 20): ");
    scanf("%d", &n);

    // Input array elements
    printf("Enter %d elements:\n", n);
    for(i = 0; i < n; i++) {
        printf("arr[%d]: ", i);
        scanf("%d", &arr[i]);
    }

    // Input position to delete
    printf("Enter position to delete (0 to %d): ", n - 1);
    scanf("%d", &pos);

    // Check for valid position
    if(pos < 0 || pos >= n) {
        printf("Invalid position!\n");
    } else {
        // Shift elements to the left
        for(i = pos; i < n - 1; i++) {
            arr[i] = arr[i + 1];
        }
        n--; // Decrease size

        // Display updated array
        printf("\nArray after deletion:\n");
        for(i = 0; i < n; i++) {
            printf("arr[%d] = %d\n", i, arr[i]);
        }
    }

    return 0;
}

🧾 Step-by-Step Explanation

🔹 Step 1: Include Header File

#include <stdio.h>

This header provides essential input/output functions:

• printf() for displaying output
• scanf() for reading user input
• Other standard I/O operations

🔹 Step 2: Declare Variables and Array

int arr[20], n, i, pos;

• arr[20]: Array with maximum capacity of 20 elements
• n: Current number of elements in the array
• pos: Position of element to be deleted
• i: Loop counter variable

🔹 Step 3: Input Size and Elements of Array

printf("Enter number of elements (max 20): ");
scanf("%d", &n);

for(i = 0; i < n; i++) {
    scanf("%d", &arr[i]);
}

• Gets the current size of the array (n ≤ 20)
• Collects each element from the user
• Stores elements sequentially in the array

🔹 Step 4: Input Position to Delete

printf("Enter position to delete (0 to %d): ", n - 1);
scanf("%d", &pos);

• Gets the index of element to be removed
• Valid positions are between 0 and n-1
• Shows user the valid range in the prompt

🔹 Step 5: Validate the Position

if(pos < 0 || pos >= n) {
    printf("Invalid position!\n");
}

• Checks if position is negative
• Checks if position exceeds array bounds
• Provides error message for invalid input

🔹 Step 6: Shift Elements to the Left

for(i = pos; i < n - 1; i++) {
    arr[i] = arr[i + 1];
}
n--;

• Starts from deletion position
• Moves each element one position left
• Overwrites the deleted element
• Decreases array size counter (n)

🔹 Step 7: Display the Updated Array

for(i = 0; i < n; i++) {
    printf("arr[%d] = %d\n", i, arr[i]);
}

• Prints all elements after deletion
• Shows both index and value for each element
• Verifies the successful deletion

🧪 Sample Output

Enter number of elements (max 20): 5
Enter 5 elements:
arr[0]: 10
arr[1]: 20
arr[2]: 30
arr[3]: 40
arr[4]: 50
Enter position to delete (0 to 4): 2

Array after deletion:
arr[0] = 10
arr[1] = 20
arr[2] = 40
arr[3] = 50

📌 Key Concepts Covered

Array Operations

Manipulating fixed-size collections of elements in memory

Element Deletion

Removing elements at specific positions by shifting elements

Left Shifting

Moving array elements to lower indices to fill deletion gap

Input Validation

Ensuring position is within valid bounds (0 to current size-1)

Size Management

Tracking and updating the current number of elements in the array