#include <iostream>
using namespace std;

int main() {
    int num;
    
    cout << "Enter a number: ";
    cin >> num;
    
    if (num % 2 == 0) {
        cout << num << " is even" << endl;
    } else {
        cout << num << " is odd" << endl;
    }
    
    return 0;
}

Enter a number: 7
7 is odd

Check Even or Odd in C++

This program determines whether a number is even or odd. This is one of the most fundamental programs in programming, teaching basic conditional logic, the modulo operator, and decision-making. Understanding even/odd is essential for many algorithms and problem-solving scenarios.

What are Even and Odd Numbers?

Even numbers:

• Divisible by 2 without remainder
• Examples: 0, 2, 4, 6, 8, 10, 12, ...
• When divided by 2, remainder is 0

Odd numbers:

• Not divisible by 2 (leave remainder 1)
• Examples: 1, 3, 5, 7, 9, 11, 13, ...
• When divided by 2, remainder is 1

Understanding the Modulo Operator (%)

The expression:

num % 2

means: "Divide num by 2 and give me the remainder."

Key properties:

• Even numbers always leave remainder ## 0 when divided by 2
• Odd numbers always leave remainder ## 1 when divided by 2

Examples:

• 10 % 2 → 0 (10 is even)
• 13 % 2 → 1 (13 is odd)
• 0 % 2 → 0 (zero is even)
• 7 % 2 → 1 (7 is odd)

The if-else Condition

if (num % 2 == 0)
cout << num << " is even" << endl;
else
cout << num << " is odd" << endl;

How it works:

If condition is true (num % 2 == 0):

• Number is even
• Print: "num is even"

If condition is false (num % 2 != 0):

• Number is odd
• Print: "num is odd"

Summary

• Even numbers: divisible by 2 (remainder 0)
• Odd numbers: not divisible by 2 (remainder 1)
• Use modulo operator (%) to check remainder
• num % 2 == 0 means even, else odd
• This is a fundamental pattern used in many programs

This program teaches:

• Modulo operator for remainder calculation
• Conditional statements (if-else)
• Decision-making in programming
• Basic input/output operations

Understanding even/odd checking is essential for:

• Many algorithmic problems
• Pattern recognition
• Array manipulation
• Mathematical programming