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C# Booleans

A bool is a type that holds one of two values, true or false. A comparison makes a bool value from two other values.

A bool value

A bool variable holds true here. Printing it shows the word True with a capital T.

using System;

class Program
{
    static void Main(string[] args)
    {
        bool isReady = true;
        Console.WriteLine(isReady);
    }
}

Two comparisons

A comparison checks two values and gives a bool result. The first test here is true, and the second test is false.

using System;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(10 > 5);
        Console.WriteLine(10 < 5);
    }
}

Equal and not equal

The == sign tests equality, and != tests the opposite. The two lines print True and then False.

using System;

class Program
{
    static void Main(string[] args)
    {
        int score = 7;
        Console.WriteLine(score == 7);
        Console.WriteLine(score != 7);
    }
}

Example

using System;

class Program
{
    static void Main(string[] args)
    {
        int age = 20;
        int points = 45;
        bool canEnter = age >= 18;
        bool hasWon = points == 50;
        Console.WriteLine("Can enter: " + canEnter);
        Console.WriteLine("Has won: " + hasWon);
    }
}

Key points

  • A bool holds either true or false.
  • Printing a bool shows True or False, each with a capital letter.
  • The sign > asks whether the left value is greater than the right value.
  • The sign >= means greater than or equal to.
  • The sign == asks whether two values are equal.
  • The sign != asks whether two values are not equal.

In this example, age is 20, so the test age >= 18 gives true and the first line prints Can enter: True. Points is 45, so the test points == 50 gives false. The second line prints Has won: False.

Try it Yourself

Edit the code, then press Run.

Running is simulated

Exercise

What does the comparison 5 == 5 print?