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Asked: 2026-05-10T17:23:16+00:00

Sample code that shows how to create threads using MFC declares the thread function

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Sample code that shows how to create threads using MFC declares the thread function as both static and __cdecl. Why is the latter required? Boost threads don’t bother with this convention, so is it just an anachronism?

For example (MFC):

static __cdecl UINT MyFunc(LPVOID pParam) { ... }  CWinThread* pThread = AfxBeginThread(MyFunc, ...);

Whereas Boost:

static void func() { ... }  boost::thread t; t.create(&func);

(the code samples might not be 100% correct as I am nowhere near an IDE).

What is the point of __cdecl? How does it help when creating threads?

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1 Answer

  1. __cdecl tells the compiler to use the C calling convention (as opposed to the stdcall, fastcall or whatever other calling convention your compiler supports). I believe, VC++ uses stdcall by default.

    The calling convention affects things such as how arguments are pushed onto the stack (or registers, in the case of fastcall) and who pops arguments off the stack (caller or callee).

    In the case of Boost. I believe it uses template specialization to figure out the appropriate function type and calling convention.

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