C# 程式設計/關鍵字/is

關鍵字is 將物件與型別進行比較，如果它們相同或屬於相同的“型別”（物件繼承該型別），則返回true。因此，該關鍵字用於檢查型別相容性，通常在強制轉換（轉換）源型別到目標型別之前，以確保不會丟擲型別轉換異常。在null 變數上使用is 始終返回false。

此程式碼片段展示了示例用法

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# 關鍵字
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
C# 特殊識別符號（上下文關鍵字）
add alias async await dynamic get global nameof partial remove set value when where yield
上下文關鍵字（用於查詢）
ascending by descending equals from group in into join let on orderby select where