C# Programming/Keywords/is

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 (Contextual Keywords)
add alias async await dynamic get global nameof partial remove set value when where yield
Contextual Keywords (Used in Queries)
ascending by descending equals from group in into join let on orderby select where