**Checking whether a number is odd or even** is a fundamental programming task that often serves as a building block for more complex algorithms.

In this detailed guide, we will explore the programming logic behind determining whether a number is odd or even, and we’ll provide code examples in several programming languages to illustrate the concept.

## Table of Contents #

## 1. Introduction

In the context of programming, it is often necessary to classify numbers into two categories: odd and even.

The concept is simple: **if a number is divisible by 2 without leaving a remainder**, it is considered an **even number**; otherwise, it is an **odd number**.

This logic forms the basis for various applications, such as conditional statements, loops, and mathematical calculations.

## 2. Understanding Odd and Even Numbers

**Even Numbers:**An even number is an integer that is exactly divisible by 2. When you divide an even number by 2, the remainder is 0. For example, 2, 4, 6, and 8 are all even numbers.**Odd Numbers:**An odd number is an integer that is not exactly divisible by 2. When you divide an odd number by 2, the remainder is 1. For example, 1, 3, 5, and 7 are all odd numbers.

## 3. Logic to Check Odd or Even

To determine whether a number is odd or even, you can use the modulo operator (%). The **modulo operator returns the remainder of a division operation**.

Here’s the logic to check for odd or even:

```
theNumber % 2 == 0 #even
theNumber % 2 == 1 #odd
```

- If
`number % 2`

equals 0, the number is even. - If
`number % 2`

equals 1, the number is odd.

## 4. Programming Examples

Let’s see how to implement this logic in various programming languages.

### 1. Python

```
def is_even_or_odd(number):
if number % 2 == 0:
return "Even"
else:
return "Odd"
```

### 2. JavaScript

```
function isEvenOrOdd(number) {
return number % 2 === 0 ? "Even" : "Odd";
}
```

### 3. PHP

```
<?php
$num = 6;
if ($num % 2 === 0) {
echo "$num is Even";
} else {
echo "$num is Odd";
}
```

### 4. Java

```
public class Main {
public static String isEvenOrOdd(int number) {
return number % 2 == 0 ? "Even" : "Odd";
}
}
```

### 5. C++

```
#include <iostream>
#include <string>
std::string isEvenOrOdd(int number) {
return number % 2 == 0 ? "Even" : "Odd";
}
int main() {
int number = 7;
std::cout << number << " is " << isEvenOrOdd(number) << std::endl;
return 0;
}
```

### 6. C#

```
using System;
public class Program
{
public static string IsEvenOrOdd(int number)
{
return number % 2 == 0 ? "Even" : "Odd";
}
public static void Main()
{
int number = 12;
Console.WriteLine($"{number} is {IsEvenOrOdd(number)}");
}
}
```

### Conclusion

Checking whether a number is odd or even is a foundational concept in programming. It is often used to create conditional statements, loops, and mathematical algorithms.

The logic is straightforward: if the remainder of a number divided by 2 is 0, it’s even; if it’s 1, it’s odd.

Understanding this logic is essential for both beginners and experienced programmers, as it forms the basis for more complex problem-solving in the programming world.