C# Program to check if a number is Positive, Negative, Odd, Even, Zero

In C#, you can determine if a number is positive, negative, odd, even, or zero using simple conditional statements and arithmetic operations. This involves checking the sign of the number and using the modulus operator to determine if a number is divisible by 2.

Logic for Number Classification

To classify a number, we use the following approaches −

• Positive/Negative/Zero: Compare the number with zero using relational operators.

• Odd/Even: Use the modulus operator (%) to check if the remainder when divided by 2 is zero.

Syntax

Following is the syntax for checking positive, negative, or zero −

if (number < 0) {
    // Negative
} else if (number == 0) {
    // Zero
} else {
    // Positive
}

Following is the syntax for checking odd or even −

if (number % 2 == 0) {
    // Even
} else {
    // Odd
}

Example

using System;

public class NumberClassification {
    public static void Main(string[] args) {
        int n = 19;
        
        Console.WriteLine("Number: " + n);
        
        // checking for odd/even
        if (n % 2 == 0) {
            Console.WriteLine("Even");
        } else {
            Console.WriteLine("Odd");
        }
        
        // checking for positive, negative or zero
        if (n < 0) {
            Console.WriteLine("Negative Number!");
        } else if (n == 0) {
            Console.WriteLine("Zero");
        } else {
            Console.WriteLine("Positive Number!");
        }
    }
}

The output of the above code is −

Number: 19
Odd
Positive Number!

Testing with Different Numbers

Example

using System;

public class NumberTest {
    public static void ClassifyNumber(int number) {
        Console.Write("Number " + number + " is: ");
        
        // Check sign
        if (number < 0) {
            Console.Write("Negative, ");
        } else if (number == 0) {
            Console.Write("Zero, ");
        } else {
            Console.Write("Positive, ");
        }
        
        // Check odd/even (zero is considered even)
        if (number % 2 == 0) {
            Console.WriteLine("Even");
        } else {
            Console.WriteLine("Odd");
        }
    }
    
    public static void Main(string[] args) {
        int[] testNumbers = {-15, -8, 0, 12, 7};
        
        foreach (int num in testNumbers) {
            ClassifyNumber(num);
        }
    }
}

The output of the above code is −

Number -15 is: Negative, Odd
Number -8 is: Negative, Even
Number 0 is: Zero, Even
Number 12 is: Positive, Even
Number 7 is: Positive, Odd

Using Methods for Reusable Code

Example

using System;

public class NumberUtility {
    public static bool IsPositive(int number) {
        return number > 0;
    }
    
    public static bool IsNegative(int number) {
        return number < 0;
    }
    
    public static bool IsEven(int number) {
        return number % 2 == 0;
    }
    
    public static bool IsOdd(int number) {
        return number % 2 != 0;
    }
    
    public static void Main(string[] args) {
        int number = -24;
        
        Console.WriteLine("Number: " + number);
        Console.WriteLine("Is Positive: " + IsPositive(number));
        Console.WriteLine("Is Negative: " + IsNegative(number));
        Console.WriteLine("Is Even: " + IsEven(number));
        Console.WriteLine("Is Odd: " + IsOdd(number));
    }
}

The output of the above code is −

Number: -24
Is Positive: False
Is Negative: True
Is Even: True
Is Odd: False

Conclusion

Checking if a number is positive, negative, odd, even, or zero in C# involves using conditional statements and the modulus operator. The modulus operator (%) determines if a number is divisible by 2, while comparison operators check the sign relative to zero.