The bool Type

The bool type represents true/false values. C# defines the values true and false using the reserved words true and false. Thus, a variable or expression of type bool will be one of these two values. Unlike some other computer languages, in C# there is no conversion defined between bool and integer values. For example, 1 does not convert to true, and 0 does not convert to false.

Here is a program that demonstrates the bool type:

 // Demonstrate bool values. using System; class BoolDemo {   public static void Main() {     bool b;     b = false;     Console.WriteLine("b is " + b);     b = true;     Console.WriteLine("b is " + b);     // a bool value can control the if statement     if(b) Console.WriteLine("This is executed.");     b = false;     if(b) Console.WriteLine("This is not executed.");     // outcome of a relational operator is a bool value     Console.WriteLine("10 > 9 is " + (10 > 9));   } }

The output generated by this program is shown here:

 b is False b is True This is executed. 10 > 9 is True

There are three interesting things to notice about this program. First, as you can see, when a bool value is output by WriteLine( ), “True” or “False” is displayed. Second, the value of a bool variable is sufficient, by itself, to control the if statement. There is no need to write an if statement like this:

 if(b == true) ...

Third, the outcome of a relational operator, such as <, is a bool value. This is why the expression 10 > 9 displays the value “True.” Further, the extra set of parentheses around 10 > 9 is necessary because the + operator has a higher precedence than the >.