C# Programming/Keywords/is

From Wikibooks, open books for an open world
Jump to: navigation, search


The is keyword compares an object to a type, and if they're the same or of the same "kind" (the object inherits the type), returns true. The keyword is therefore used to check for type compatibility, usually before casting (converting) a source type to a destination type in order to ensure that won't cause a type-cast exception to be thrown. Using is on a null variable always returns false.

This code snippet shows a sample usage:

System.IO.StreamReader reader = new StreamReader("readme.txt");
bool b = reader is System.IO.TextReader;

// b is now set to true, because StreamReader inherits TextReader



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