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

8C < T >	box valTypeToken	Convert a value type (of the type specified in valTypeToken) to a true object reference.

The stack transitional behavior, in sequential order, is:

[The 'ordered' type of list has not been implemented in the ECMA stylesheet.]

A value type has two separate representations within the Common Language Infrastructure (CLI):

• A 'raw' form used when a value type is embedded within another object or on the stack.

• A 'boxed' form, where the data in the value type is wrapped (boxed) into an object so it can exist as an independent entity.

The box instruction converts the 'raw' (unboxed) value type into an object reference (type O). This is accomplished by creating a new object and copying the data from the value type into the newly allocated object. valTypeToken is a metadata token indicating the type of the value type on the stack.

OutOfMemoryException is thrown if there is insufficient memory to satisfy the request.

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

The following ILGenerator.Emit(OpCode) method overload can use the box opcode:

• ILGenerator.Emit(OpCode, Type)

Namespace: System.Reflection.Emit
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0