C# Programming/Keywords/typeof

The typeof keyword returns an instance of the System.Type class when passed a name of a class. It is similar to the sizeof|sizeof keyword in that it returns a value instead of starting a section (block) of code (see if, try, while).

An example:

using System;

namespace MyNamespace
{
    class MyClass
    {
        static void Main(string[] args)
        {
            Type t = typeof(int);
            Console.Out.WriteLine(t.ToString());
            Console.In.Read();
        }
    }
}

The output will be:

System.Int32

It should be noted that unlike sizeof, only class names themselves and not variables can be passed to typeof as shown here:

using System;

namespace MyNamespace
{
    class MyClass2
    {
        static void Main(string[] args)
        {
            char ch;
            
            // This line will cause compilation to fail
            Type t = typeof(ch);
            Console.Out.WriteLine(t.ToString());
            Console.In.Read();
        }
    }
}

Sometimes, classes will include their own GetType() method that will be similar, if not identical, to typeof.

C# Keywords
abstract as base bool break byte case catch char checked class const continue decimal default delegate do double else enum event explicit extern false finally fixed float for foreach goto if implicit in int interface internal is lock long namespace new null object operator out override params private protected public readonly ref return sbyte sealed short sizeof stackalloc static string struct switch this throw true try typeof uint ulong unchecked unsafe ushort using var virtual void volatile while
Special C# Identifiers
add alias get global partial remove set value where yield