Castclass Field
TOC
Collapse the table of content
Expand the table of content

OpCodes.Castclass Field

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

[Visual Basic]
Public Shared ReadOnly Castclass As OpCode
[C#]
public static readonly OpCode Castclass;
[C++]
public: static OpCode Castclass;
[JScript]
public static var Castclass : OpCode;

Remarks

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 constructor overload can use the castclass opcode:

  • ILGenerator.Emit(OpCode, Type)

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

OpCodes Class | OpCodes Members | System.Reflection.Emit Namespace

Show:
© 2016 Microsoft