About function Invocation methods __stdcall and __cdecl detailed _c language

About function call Way __stdcall and __cdecl detailed

__stdcall

__cdecl

The similarities and differences between the two points

Instance

__stdcall

__stdcall's full name is standard call. is the standard invocation method for C + +.

function parameters are in the stack order from right to left. function returns with the RETN x instruction, where x is the number of bytes to adjust the stack. This method is called Automatic clearing stack. That is, the number of parameters of the called function is fixed, the caller must strictly follow the definition of the pass parameters, one is not much, a lot.

__cdecl

__cdecl's full name is C declaration, which is the default function invocation of C language.

function parameters are in the stack order from right to left. function to act as a RET instruction when returning functions. Manually clearing the stack by the caller. The called function supports variable parameters. The caller manually balances the stack based on the number of arguments passed in at the time of the call.

The similarities and differences between the two points

Same point

Parameter stack order is the same: from right to left

Different points

Stack balance mode is different: __stdcall automatic cleaning stack, __cdecl manual cleaning stack.

Return instruction is different: _stdcall uses RETN x, __CDECL uses RET

The decorated name of the compiled function is different: suppose there is a function int foo (int a, int b), with the __stdcall compiled function named _foo@8, and the __cdecl compiled function named _foo.

Instance

Functions that support variable parameters must be defined as __cdecl, such as:

int printf (char *fmt, ...);

Definition of __stdcall and __cdecl in windef.h

 #define CALLBACK   __stdcall
 #define WINAPI    __stdcall
 #define WINAPIV   __cdecl
 #define Apientry   WINAPI
 #define Apiprivate  __stdcall
 #define PASCAL    __stdcall
 #define CDECL _ Cdecl
 #ifndef cdecl
 #define CDECL _cdecl
 #endif

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