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In this tutorial, you will learn how to print all even numbers between 1 to 100 using while loop conditional statement in c. In this article, we will go through examples, logic, algorithms, and program explanations for your better understanding.

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 the even numbers between 1 and 100 using a while loop. The program should take an integer input from the user and print all the even numbers within a specified range using a while loop. You can refer our below example.

Example

Output:
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100

Algorithm

1. Start the program.
2. Declare a variable num to represent the current number, initialized to 1.
3. Print the header message: “Even numbers between 1 and 100:”
4. Enter the while loop with the condition num <= 100.
   • Check if the current number num is even using the modulo operator (num % 2 == 0).
   • If it is even, print the value of num.
   • Increment num by 1.
5. Exit the while loop.
6. Print a new line to separate the output.
7. End the program.

Logic used to solve this problem

• Initialize a num variable to 1.
• Use a while loop that runs as long as the num is less than or equal to 100.
• Inside the loop, check if the num is an even number using the modulo (%) operator.
• If the num is even, print the number.
• Increment the num by 1 in each iteration.
• Continue the loop until the counter reaches 100.
• Finish the program.

Program to Print all even numbers between 1 to 100

#include <stdio.h>
int main() {
    int num = 1;
    printf("Even numbers between 1 and 100: ");
    while (num <= 100) {
        if (num % 2 == 0) {
            printf("%d ", num);
        }
        num++;
    }
    printf("\n");
    return 0;
}

Output

Even numbers between 1 and 100: 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 

Program Explanation

• The program initializes a variable num to 2, which represents the first even number to be printed.
• The program enters a while loop with the condition num <= 100 to iterate through numbers from 2 to 100.
• Inside the while loop, it prints the value of num on the screen.
• It then increments the value of num by 2 since the next even number will be 2 greater than the current one.
• The loop continues until num exceeds the value of 100.
• Once the while loop is complete, the program ends.

Conclusion

The C program successfully prints all the even numbers between 1 and 100 using a while loop. By checking the divisibility of each number by 2, it identifies the even numbers and prints them on a single line. I hope this program is clear to you.