Boolean Type and Operators

C#’s bool type (aliasing the System.Boolean type) is a logical value that can be assigned the literal true or false.

Although a Boolean value requires only one bit (zero or one) of storage, the runtime will use one or two bytes of memory, as this is the minimum chunk that the runtime and processor can efficiently work with. To avoid space-inefficiency in the case of arrays, the Framework provides a BitArray class in the System.Collections namespace, which is designed to use just one bit per Boolean value.

Equality and Comparison Operators

= = and != test for equality and inequality of any type, but always return a bool value. Value types typically have a very simple notion of equality:

	int x = 1, y = 2, z = 1;
	Console.WriteLine (x == y);         // False
	Console.WriteLine (x == z);         // True

For reference types, equality, by default, is based on reference, as opposed to the actual value of the underlying object:

	public class Dude
	{
	  public string Name;
	  public Dude (string n) { Name = n; }
	}
	Dude d1 = new Dude ("John");
	Dude d2 = new Dude ("John");
	Console.WriteLine (d1 == d2);       // False
	Dude d3 = d1;
	Console.WriteLine (d1 == d3);       // True

The comparison operators, <, >, <=, and >=, work for all numeric types, but should be used with caution with real numbers (see the previous section “Real Number Rounding Errors”). The comparison operators also work on enum type members, by comparing their underlying integral values.

We’ll explain the equality and comparison operators ...

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