What is the condition for even numbers in C?

The condition to identify an even number in C is (number % 2 == 0). This checks if the remainder of the number divided by 2 is exactly zero.

Is there a difference between using while and do-while loops for this?

Both loops will produce the same output for this task. However, a 'while' loop checks the condition before executing the code, whereas a 'do-while' loop ensures the code block runs at least once before checking the condition.

How to Print Even Numbers from 1 to N in C (Using While & Do-While Loops)

Q: How to print even numbers from 1 to N in C?

To print even numbers, use a loop that runs from 1 to N. Within the loop, use the modulus operator to check if the number is divisible by 2. If the condition (number % 2 == 0) is true, the number is even and should be printed.

In this tutorial, we will learn how to print even numbers from 1 to N using while and do-while loops in C. Understanding how to control loop output is a fundamental skill that frequently pops up in coding interviews and university exams.

Even numbers are simply those that can be divided by 2 without leaving a remainder—like 2, 4, 6, 8, and so on.

What is an even number in C?

An even number is any integer that is perfectly divisible by 2. In programming, we identify these by checking if the remainder is zero when divided by 2.

How to print even numbers from 1 to N in C?

The logic is straightforward: we run a loop from 1 to N and use the modulus operator to filter the numbers. If the condition (number % 2 == 0) is true, we print it.

💻 C Program Code to Print Even Numbers

#include <stdio.h>

int main()
{
    int c = 1, n;

    printf("Enter the value of N: ");
    scanf("%d", &n);

    printf("Even Numbers from 1 to %d:\n", n);

    while(c <= n)
    {
        // Using % 2 == 0 to catch even numbers
        if(c % 2 == 0)
            printf("%d ", c);

        c++;
    }

    return 0;
}

📌 Output

Enter the value of N: 7 Even Numbers from 1 to 7: 2 4 6

🧠 How This Program Works

Step 1: Take the input value N from the user to set the range.
Step 2: Initialize a counter (c) starting at 1.
Step 3: Run the loop as long as the counter is less than or equal to N.
Step 4: Check the even condition (c % 2 == 0).
Step 5: If the remainder is 0, print the number.
Step 6: Increment the counter by 1 and repeat the process until the loop finishes.

⚡ Key Concept: The Modulus Operator

In C programming, we use the modulus (%) operator to find the remainder of a division. It is the most efficient way to check if a number is even.

If a number divided by 2 gives a remainder of 0, that number is even. Otherwise, it is odd. This simple check (c % 2 == 0) is the foundation of many data filtering tasks you will encounter in real-world programming.

🚀 Practice Question

Try modifying this program to print:

Odd and even numbers from 1 to N
Sum of Odd numbers between range

Frequently Asked Questions (FAQs)

Q: How can I print even numbers from 1 to N in C?

A: Run a loop from 1 to N and check each number using (number % 2 == 0). If the condition is true, print the number.

Q: What is the easiest way to print even numbers in C?

A: The easiest way is to start from 2 and increase by 2 each time (2, 4, 6, 8...). This avoids checking every number.

Q: What condition is used to check even numbers in C?

A: We use (number % 2 == 0). If the remainder is 0, the number is even.

Q: Can I use both while and do-while loops for this program?

A: Yes, both loops work. The only difference is that a do-while loop runs at least once before checking the condition.

Q: Why is the modulus (%) operator important in C?

A: The modulus operator helps find the remainder. It is very useful for checking conditions like even/odd numbers.

Q: Is this question important for exams or interviews?

A: Yes. This is a very common beginner-level question and helps you understand loops and conditions clearly.

🔥 Print Even Numbers in C using Do-While Loop: A Step-by-Step Guide

Let’s learn how to print even numbers from 1 to N using a do-while loop in C. Even numbers are those which are divisible by 2, like 2, 4, 6, 8…

Code

#include <stdio.h>

int main()
{
  int c = 1, n;

  printf("Enter the value of N: ");
  scanf("%d", &n);

  printf("Even Numbers from 1 to %d:\n", n);

  do
  {
    if(c % 2 == 0)
      printf("%d ", c);
    c++;
  } while(c <= n);

  return 0;
}

Output

Input: 7
Output: 2 4 6

Explanation

We start from 1 and check each number. If it is divisible by 2, we print it. The loop runs at least once because it’s a do-while loop.

🔥 C While & Do-While Loop Programs (Practice Set 1)

🚀 Practice the most important C while loop and do-while loop programs asked in exams and interviews. These beginner-to-advanced problems will help you master loop concepts quickly.

C Program to Print Odd Numbers from 1 to N (While & Do-While)
Learn how to print odd numbers using loops in C. A basic problem to understand loop iteration.
C Program to Print Even Numbers from 1 to N
Understand how to display even numbers using while and do-while loops in C.
C Program to Print Uppercase Alphabets (A to Z)
Print all uppercase letters using loops. Helps in understanding ASCII values and iteration.
C Program to Print Lowercase Alphabets (a to z)
Simple loop program to print lowercase alphabets in C.
C Program to Print Numbers from 1 to 10
Basic beginner example to understand number printing using loops.
C Program to Print Multiplication Table using While Loop
Take user input and generate a multiplication table. Common interview question.
C Program to Check Positive, Negative or Zero
Check number type continuously using loops until user exits.
C Program to Find Factorial using While Loop
Calculate factorial using loops. Important for coding interviews.
C Program to Find Sum of First N Natural Numbers
Compute sum from 1 to N using loop logic. Core beginner problem.
C Program to Print Prime Numbers from 1 to N
Learn prime number logic using nested loops in C programming.
C Program to Print Armstrong Numbers from 1 to N
Understand Armstrong number logic using loops and mathematical operations.
C Program to Print Leap Years using While Loop
Find leap years using conditions and loops. Useful for real-world logic building.
C Program to Reverse a Number using While Loop
Reverse digits of a number using loops. Frequently asked interview question.

📘 Practice/Assignment Set 2: C While & Do-While Loop Series Programs

1. C Program to Find Sum of Squares from 1 to N using While Loop
Learn how to calculate the sum of squares (1² + 2² + 3² + ... + N²) using while and do-while loops in C. This is a commonly asked logic-building problem in exams and coding interviews.

2. C Program to Find Sum of First N Natural Numbers using While Loop
Write a C program to calculate the sum of natural numbers (1 + 2 + 3 + ... + N) using loops. A basic and important program for beginners learning loop concepts.

3. C Program to Find Sum of Series (1/1! + 2/2! + ... + N/N!)
Practice a slightly advanced loop problem by computing the sum of factorial-based series using while or do-while loops. Helps strengthen logic and mathematical programming skills.

4. C Program to Find Sum of Harmonic Series (1 + 1/2 + 1/3 + ... + 1/N)
Learn how to calculate the harmonic series using loops in C. This program improves understanding of floating-point calculations and loop control.

5. C Program to Find Sum of Series (1 + 3²/3³ + 5²/5³ + ... up to N Terms)
Solve an advanced series-based problem using while loop logic. This type of question is frequently asked in competitive programming and technical interviews.

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