C# Booleans

Very often, in programming, you will need a data type that can only have one of two values, like

C# Booleans

Very often, in programming, you will need a data type that can only have one of two values, like:

  • YES / NO
  • ON / OFF
  • TRUE / FALSE
  • For this, C# has a bool data type, which can take the values true or false.

    Boolean Values

    A boolean type is declared with the bool keyword and can only take the values true or false:

    Example

    bool isCSharpFun = true;
    bool isFishTasty = false;
    Console.WriteLine(isCSharpFun);   // Outputs True
    Console.WriteLine(isFishTasty);   // Outputs False
    

    Try it Yourself »

    However, it is more common to return boolean values from boolean expressions, for conditional testing (see below).

    Boolean Expression

    A Boolean expression is a C# expression that returns a Boolean value: True or False.

    You can use a comparison operator, such as the greater than (>) operator to find out if an expression (or a variable) is true:

    Example

    int x = 10;
    int y = 9;
    Console.WriteLine(x > y); // returns True, because 10 is higher than 9
    

    Try it Yourself »

    Or even easier:

    Example

    Console.WriteLine(10 > 9); // returns True, because 10 is higher than 9
    

    Try it Yourself »

    In the examples below, we use the equal to (==) operator to evaluate an expression:

    Example

    int x = 10;
    Console.WriteLine(x == 10); // returns True, because the value of x is equal to 10
    

    Try it Yourself »

    Example

    Console.WriteLine(10 == 15); // returns False, because 10 is not equal to 15
    

    Try it Yourself »

    The boolean value of an expression is the basis for all C# comparisons and conditions.

    You will learn more about conditions in the next chapter.

    C# Exercises

    Test Yourself With Exercises

    Exercise:

    Fill in the missing parts to print the values True and False:

     isCodingFun = true;
     isFishTasty = false;
    Console.WriteLine();
    Console.WriteLine();
    

    Start the Exercise