How do you check if an integer is even or odd?

Determining whether an integer is even or odd is a fundamental task in programming. This involves checking if the integer is divisible by 2 without leaving a remainder. Let’s break down the concept, provide an example, and show how to implement this in different programming languages.

Understanding the Problem

An integer is classified as:

• Even if it is divisible by 2 with no remainder. Mathematically, an integer ( n ) is even if ( n \% 2 = 0 ), where % is the modulo operator.
• Odd if it is not divisible by 2 evenly. Mathematically, an integer ( n ) is odd if ( n \% 2 = 1 ) (or ( n \% 2 = -1 ) in some languages that handle negative numbers differently).

Example

Consider the integer 7.

1. Even Check:

• ( 7 \% 2 = 1 )
• Since the result is not 0, 7 is odd.

Consider the integer 8.

1. Even Check:

• ( 8 \% 2 = 0 )
• Since the result is 0, 8 is even.

Step-by-Step Approach

1. Input: Read or receive the integer.
2. Modulo Operation: Use the modulo operator to find the remainder when the integer is divided by 2.
3. Check Remainder:

• If the remainder is 0, the integer is even.
• If the remainder is 1 (or -1 depending on language), the integer is odd.

1. Output: Display or return whether the integer is even or odd.

Code Examples

1. Python

def check_even_odd(n):
    if n % 2 == 0:
        return "Even"
    else:
        return "Odd"

# Example usage
n = 7
print(f"The number {n} is:", check_even_odd(n))

n = 8
print(f"The number {n} is:", check_even_odd(n))

2. JavaScript

function checkEvenOdd(n) {
    if (n % 2 === 0) {
        return "Even";
    } else {
        return "Odd";
    }
}

// Example usage
let n = 7;
console.log(`The number ${n} is: ${checkEvenOdd(n)}`);

n = 8;
console.log(`The number ${n} is: ${checkEvenOdd(n)}`);

3. Java

public class Main {
    public static String checkEvenOdd(int n) {
        if (n % 2 == 0) {
            return "Even";
        } else {
            return "Odd";
        }
    }

    public static void main(String[] args) {
        int n = 7;
        System.out.println("The number " + n + " is: " + checkEvenOdd(n));

        n = 8;
        System.out.println("The number " + n + " is: " + checkEvenOdd(n));
    }
}

4. C++

#include <iostream>

std::string checkEvenOdd(int n) {
    if (n % 2 == 0) {
        return "Even";
    } else {
        return "Odd";
    }
}

int main() {
    int n = 7;
    std::cout << "The number " << n << " is: " << checkEvenOdd(n) << std::endl;

    n = 8;
    std::cout << "The number " << n << " is: " << checkEvenOdd(n) << std::endl;

    return 0;
}

5. C

using System;

class Program {
    public static string CheckEvenOdd(int n) {
        if (n % 2 == 0) {
            return "Even";
        } else {
            return "Odd";
        }
    }

    static void Main() {
        int n = 7;
        Console.WriteLine("The number " + n + " is: " + CheckEvenOdd(n));

        n = 8;
        Console.WriteLine("The number " + n + " is: " + CheckEvenOdd(n));
    }
}

To determine if an integer is even or odd, you use the modulo operator to find the remainder when the integer is divided by 2. If the remainder is 0, the number is even; otherwise, it is odd. The provided code examples in Python, JavaScript, Java, C++, and C# demonstrate this concept using the syntax and features of each language. This simple check is a fundamental operation in programming and forms the basis for more complex algorithms and logic.