Tutorials 参考 练习 Menu
Paid Courses

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

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:


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

来试试吧 »

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:


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

来试试吧 »

Or even easier:


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

来试试吧 »

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


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

来试试吧 »


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

来试试吧 »

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# 练习

Test Yourself With 练习


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

 isCodingFun = true;
 isFishTasty = false;

Start the Exercise

W3Schools is optimized for learning and training. 示例 might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy.

Copyright 1999-2021 by Refsnes Data. All Rights Reserved.
W3Schools is Powered by W3.CSS.