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