The calling conventions in this class describe how functions pass arguments and return values. They specify the order in which parameters are set up for the called functions, where the parameters are stored (in registers or in memory), and who (caller or called function) is responsible for cleaning up the stack after the function returns. For example:

• CALLCONV.CC_CDECL uses the naming and calling conventions of the C language. The caller pushes the parameters onto the stack in reverse (right-to-left) order, and cleans the stack after the function returns. This calling convention enables you to call functions with varargs, which makes it appropriate for use with methods that accept a variable number of parameters, such as the C run-time functions printf, _printf_l, wprintf, _wprintf_l.

• CALLCONV.CC_PASCAL uses the Pascal calling convention. The caller pushes the parameters onto the stack in left-to-right order. The called function cleans the stack before returning.

• CALLCONV.CC_STDCALL is the standard calling convention for Win32 functions. It is the default convention for calling unmanaged functions with platform invoke. The caller pushes the parameters onto the stack in reverse (right to left) order, and the called function cleans the stack before returning.

• CALLCONV.CC_SYSCALL is similar to CDECL in that arguments are pushed from right to left. The EAX, ECX, and EDX registers are not preserved.

These calling convention identifiers are used by the dnprdnshort, the wince platform, and by Automation.

For additional information about System.Runtime.InteropServices.ComTypes.CALLCONV, see the MSDN Library.

The common language runtime throws an exception when a COM method in native code returns an HRESULT. For more information, see How to: Map HRESULTs and Exceptions.

Namespace: System.Runtime.InteropServices.ComTypes
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0
Since: .NET 2.0