C Program to Sort an Array in Ascending and Descending Order

Introduction

Sorting an array involves arranging the elements in a specific order. This guide will show you how to write a C program to sort an array in both ascending and descending order using the Bubble Sort algorithm.

Problem Statement

Create a C program that:

• Takes the size of the array as input from the user.
• Takes the elements of the array as input.
• Sorts the array in ascending order and displays it.
• Sorts the array in descending order and displays it.

Example:

• Input: Array = [5, 2, 9, 1, 5, 6]
• Output:
  • Ascending Order = [1, 2, 5, 5, 6, 9]
  • Descending Order = [9, 6, 5, 5, 2, 1]

Solution Steps

1. Include the Standard Input-Output Library: Use #include <stdio.h> to include the standard input-output library, which is necessary for using printf and scanf functions.
2. Write the Main Function: Define the main function, which is the entry point of every C program.
3. Declare Variables: Declare variables to store the array size, the array elements, and temporary variables for swapping.
4. Input the Array Size: Use scanf to take input from the user for the size of the array.
5. Input the Array Elements: Use a loop to take input from the user for the elements of the array.
6. Sort the Array in Ascending Order: Use the Bubble Sort algorithm to sort the array in ascending order.
7. Display the Array in Ascending Order: Use printf to display the sorted array.
8. Sort the Array in Descending Order: Use the Bubble Sort algorithm to sort the array in descending order.
9. Display the Array in Descending Order: Use printf to display the sorted array.

C Program

#include <stdio.h>

/**
 * C Program to Sort an Array in Ascending and Descending Order
 * Author: https://www.javaguides.net/
 */
int main() {
    // Step 1: Declare variables to hold the array size, elements, and a temporary variable for swapping
    int n, temp;

    // Step 2: Prompt the user to enter the size of the array
    printf("Enter the number of elements in the array: ");
    scanf("%d", &n);

    // Step 3: Declare an array to hold the elements
    int arr[n];

    // Step 4: Input the array elements
    printf("Enter %d elements:\n", n);
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    // Step 5: Sort the array in ascending order using Bubble Sort
    for (int i = 0; i < n-1; i++) {
        for (int j = 0; j < n-i-1; j++) {
            if (arr[j] > arr[j+1]) {
                // Swap the elements
                temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }

    // Step 6: Display the array in ascending order
    printf("Array in ascending order: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    // Step 7: Sort the array in descending order using Bubble Sort
    for (int i = 0; i < n-1; i++) {
        for (int j = 0; j < n-i-1; j++) {
            if (arr[j] < arr[j+1]) {
                // Swap the elements
                temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }

    // Step 8: Display the array in descending order
    printf("Array in descending order: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    return 0;  // Step 9: Return 0 to indicate successful execution
}

Explanation

Step 1: Declare Variables

• The variable n is declared to store the size of the array. temp is used as a temporary variable for swapping elements during sorting.

Step 2: Input the Array Size

• The program prompts the user to enter the size of the array using printf. The scanf function then reads the input and stores it in the variable n.

Step 3: Declare the Array

• The program declares an array arr of size n to hold the elements provided by the user.

Step 4: Input the Array Elements

• The program uses a for loop to take input for each element of the array. The loop iterates from 0 to n-1, reading the elements using scanf.

Step 5: Sort the Array in Ascending Order

• The program uses the Bubble Sort algorithm to sort the array in ascending order:
  • The outer loop iterates through the entire array n-1 times.
  • The inner loop compares each element with its adjacent element and swaps them if they are in the wrong order. The smallest element "bubbles" up to its correct position at the beginning of each pass.

Step 6: Display the Array in Ascending Order

• After the sorting process is complete, the program displays the sorted array using a for loop and the printf function.

Step 7: Sort the Array in Descending Order

• The program uses the Bubble Sort algorithm again, but this time to sort the array in descending order:
  • The outer loop iterates through the entire array n-1 times.
  • The inner loop compares each element with its adjacent element and swaps them if they are in the wrong order. The largest element "bubbles" up to its correct position at the beginning of each pass.

Step 8: Display the Array in Descending Order

• After the sorting process is complete, the program displays the sorted array in descending order using a for loop and the printf function.

Step 9: Return 0

• The return 0; statement indicates that the program executed successfully.

Output Example

Example:

Enter the number of elements in the array: 5
Enter 5 elements:
64
25
12
22
11
Array in ascending order: 11 12 22 25 64 
Array in descending order: 64 25 22 12 11

Another Example:

Enter the number of elements in the array: 4
Enter 4 elements:
9
1
4
7
Array in ascending order: 1 4 7 9 
Array in descending order: 9 7 4 1

Conclusion

This C program demonstrates how to sort an array in both ascending and descending order using the Bubble Sort algorithm. It covers basic concepts such as arrays, loops, and sorting algorithms, making it a useful example for beginners learning C programming.