C# Booleans

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:

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

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

Or even easier:

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

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

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

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