The following list shows the implementation of this calling convention.

The /Gz compiler option specifies __stdcall for all functions not explicitly declared with a different calling convention.

Functions declared using the __stdcall modifier return values the same way as functions declared using __cdecl.

On Itanium Processor Family (IPF) and x64 processors, __stdcall is accepted and ignored by the compiler; on IPF, by convention, parameters are passed in register.

For non-static class functions, if the function is defined out-of-line, the calling convention modifier does not have to be specified on the out-of-line definition. That is, for class non-static member methods, the calling convention specified during declaration is assumed at the point of definition. Given this class definition,

struct CMyClass {
   void __stdcall mymethod();
};

this

void CMyClass::mymethod() { return; }

is equivalent to this

void __stdcall CMyClass::mymethod() { return; }

In the following example, use of __stdcall results in all WINAPI function types being handled as a standard call:

// Example of the __stdcall keyword
#define WINAPI __stdcall
// Example of the __stdcall keyword on function pointer
typedef BOOL (__stdcall *funcname_ptr)(void * arg1, const char * arg2, DWORD flags, ...);

Reference