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In this tutorial, you will learn how to write a C program to print all natural numbers in reverse order using a while loop conditional statement. We will explore examples and algorithms with explanations for your better understanding of this problem.

Required Knowledge

• C Programming Basics
• C Programming Operators
• C printf and Scanf
• While loop in C

Problem Statement

You have to Write a C Program that prints all natural numbers in reverse order using a while loop. The program provides a solution to print natural numbers in reverse order using a while loop in the C programming language. For a better understanding, you can see the below example. It will help you to understand what exactly you have to achieve.

Example

Output:
10
9
8
7
6
5
4
3
2
1

Here the input is not given by the user. We have kept the hardcoded value 10 and printed them in reverse order.

Algorithm

1. Start the program.
2. Declare the variable num to store the current number.
3. Initialize num to 10.
4. Enter the while loop with the condition num >= 1.
   • Print the value of num.
   • Decrement num by 1.
5. Exit the while loop.
6. End the program.

Logic used to solve this problem

• Declare a variable to hold the maximum limit of the natural numbers.
• Prompt the user to enter the maximum limit.
• Read and store the entered maximum limit in the variable.
• Initialize a counter variable with the maximum limit.
• Use a while loop that runs as long as the counter is greater than or equal to 1.
• Inside the loop, print the value of the counter.
• Decrement the counter by 1 in each iteration.
• Continue the loop until the counter becomes less than 1.
• Finish the program.

Program to Print all Natural numbers in Reverse Order

#include <stdio.h>
int main() {
    int num = 10;
    while (num >= 1) {
        printf("%d\n", num);
        num--;
    }
    return 0;
}

Output

10
9
8
7
6
5
4
3
2
1

Program Explanation

• The program takes input for the value of n from the user.
• It initializes a variable num to n, which represents the starting point for printing the numbers.
• The program enters a while loop with the condition num >= 1 to iterate through numbers from n to 1.
• Inside the while loop, it prints the value of num on the screen.
• It then decrements the value of num by 1 to move on to the next number in reverse order.
• The loop continues until num reaches 1.
• Once the while loop is complete, the program ends.

Conclusion

The C program successfully prints all natural numbers in reverse order using a while loop. By starting with an initial value and decrementing it in each iteration, the program displays the numbers in descending order on the screen.