Using Typeof Operator in C#

Using typeof

// Demonstrate typeof.
using System;
using System.IO;
class UseTypeof {
static void Main() {
Type t = typeof(StreamReader);
Console.WriteLine(t.FullName);
if(t.IsClass) Console.WriteLine("Is a class.");
if(t.IsAbstract) Console.WriteLine("Is abstract.");
else Console.WriteLine("Is concrete.");
}
}
This program outputs the following:
System.IO.StreamReader
Is a class.
Is concrete.





Although useful in their own ways, the as and is operators simply test the compatibility of
two types. Often, you will need to obtain information about a type. To do this, C# supplies
the typeof operator. It retrieves a System.Type object for a given type. Using this object, you
can determine the type’s characteristics.
The typeof operator has this general form:
typeof(type)
Here, type is the type being obtained. The Type object returned encapsulates the information
associated with type.
Once you have obtained a Type object for a given type, you can obtain information about
it through the use of various properties, fields, and methods defined by Type. Type is a large
class with many members, and a discussion is deferred until the next section, where reflection
is examined. However, to briefly demonstrate Type, the following program uses three of
its properties: FullName, IsClass, and IsAbstract. To obtain the full name of the type, use
FullName. IsClass returns true if the type is a class. IsAbstract returns true if a class is abstract.