What is the condition for odd numbers in C?

The condition for odd numbers is number % 2 != 0.

Program 1: Print Odd Numbers from 1 to N using While Loop and do while loop.

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

Use a loop from 1 to N and check each number using modulus operator. If number % 2 is not equal to 0, it is an odd number.

In this tutorial, you will learn how to print odd numbers from 1 to N using a while loop in C. This is one of the most important programs asked in exams and coding interviews.

Odd numbers are numbers like 1, 3, 5, 7... (numbers not divisible by 2).

What is an odd number in C?

An odd number is a number that is not divisible by 2. Examples: 1, 3, 5, 7.

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

We use a loop and check each number using (number % 2 != 0). If true, we print it.

💻 C Program Code


#include <stdio.h>

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

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

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

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

        c++;
    }

    return 0;
}

📌 Output

Enter the value of N: 7 Odd Numbers from 1 to 7: 1 3 5 7

🧠 How This Program Works

Step 1: Take input value N from user
Step 2: Start counter from 1
Step 3: Run loop until counter ≤ N
Step 4: Check condition (c % 2 != 0)
Step 5: Print number if it is odd
Step 6: Increase counter and repeat

⚡ Key Concept

We use the modulus (%) operator to check odd numbers. If the remainder is not zero, the number is odd.

🚀 Practice Question

Try modifying this program to print:

Even numbers from 1 to N
Odd numbers between two numbers

🔥 C Program to Print Odd Numbers from 1 to N using Do-While Loop (Step-by-Step )

Want to quickly learn how to print odd numbers in C? 🤔
In this example, we will print all odd numbers from 1 to N using a do-while loop in a very simple way.

👉 Odd numbers are numbers like: 1, 3, 5, 7... (not divisible by 2)

💻 C Program Code

  scanf("%d",&n);

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

  do
  {
    if(c % 2 != 0)
      printf("%d ", c);

    c++;
  } while(c <= n);

  return 0;
}

📌 Output

Enter the value of N: 7
Odd Numbers from 1 to 7:
1 3 5 7

🧠 Easy Explanation (Understand in 30 Seconds)

✔ Step 1: Start from number 1
✔ Step 2: Check → number % 2 != 0 (means odd)
✔ Step 3: If true → print number
✔ Step 4: Increase number by 1
✔ Step 5: Repeat until it reaches N

⚡ Important Concept (Must Know)

👉 In do-while loop, the loop runs at least one time.
👉 Condition is checked after execution.
👉 This is the main difference from while loop.

🎯 Why This Program is Important?

✔ Very common in exams
✔ Frequently asked in interviews
✔ Builds strong loop logic
✔ Helps in solving advanced problems

🚀 Try This Yourself

👉 Modify the program to print even numbers
👉 Try printing numbers in reverse order
👉 Try using only while loop and compare output

🔥 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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