OpCodes.Castclass Field

Attempts to cast an object passed by reference to the specified class.

Namespace: System.Reflection.Emit
Assembly: mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)] 
public static readonly OpCode Castclass
/** @attribute ComVisibleAttribute(true) */ 
public static final OpCode Castclass
ComVisibleAttribute(true) 
public static final var Castclass : OpCode
Not applicable.

The following table lists the instruction's hexadecimal and Microsoft Intermediate Language (MSIL) assembly format, along with a brief reference summary:

Format

Assembly Format

Description

74 < T >

castclass class

Casts an object to a new object of type class.

The stack transitional behavior, in sequential order, is:

  1. An object reference is pushed onto the stack.

  2. The object reference is popped from the stack; the referenced object is cast as the specified class.

  3. If successful, a new object reference is pushed onto the stack.

The castclass instruction attempts to cast the object reference (type O) atop the stack to a specified class. The new class is specified by a metadata token indicating the desired class. If the class of the object on the top of the stack does not implement the new class (assuming the new class is an interface) and is not a derived class of the new class then an InvalidCastException is thrown. If the object reference is a null reference, castclass succeeds and returns the new object as a null reference.

InvalidCastException is thrown if obj cannot be cast to class.

TypeLoadException is thrown if class cannot be found. This is typically detected when a Microsoft Intermediate Language (MSIL)instruction is converted to native code rather than at runtime.

The following Emit method overload can use the castclass opcode:

  • ILGenerator.Emit(OpCode, Type)

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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