stdcall不只是一个调用约定;除了作为调用约定之外，它还允许C和C++对象之间的同构。这里有一个例子：

#define _CRT_SECURE_NO_WARNINGS // disable marking use of strcpy as error.

#include

#include

#include

class ICdeclGreeter {

public:

virtual ~ICdeclGreeter(){}

virtual void setGreeting(const char *greeting) = 0;

virtual void greet() = 0;

};

class IStdcallGreeter {

public:

virtual __stdcall ~IStdcallGreeter(){}

virtual void __stdcall setGreeting(const char *greeting) = 0;

virtual void __stdcall greet() = 0;

};

class CdeclGreeter : public ICdeclGreeter {

public:

char *greeting;

~CdeclGreeter() {

if (greeting != nullptr) {

free(greeting);

puts("[CdeclGreeter] destroyed");

}

}

void setGreeting(const char *greeting) {

this->greeting = (char *)malloc(strlen(greeting) + 1);

strcpy(this->greeting, greeting);

}

void greet() {

puts(greeting);

}

};

class StdcallGreeter : public IStdcallGreeter {

public:

char *greeting;

__stdcall ~StdcallGreeter() {

if (greeting != nullptr) {

free(greeting);

puts("[StdcallGreeter] destroyed");

}

}

void __stdcall setGreeting(const char *greeting) {

this->greeting = (char *)malloc(strlen(greeting) + 1);

strcpy(this->greeting, greeting);

}

void __stdcall greet() {

puts(greeting);

}

};

typedef struct pureC_StdcallGreeter pureC_StdcallGreeter;

typedef struct pureC_StdcallGreeterVtbl {

void (__stdcall *dtor)(pureC_StdcallGreeter *This);

void (__stdcall *setGreeting)(pureC_StdcallGreeter *This, const char *greeting);

void (__stdcall *greet)(pureC_StdcallGreeter *This);

} pureC_IStdcallGreeterVtbl;

struct pureC_StdcallGreeter {

pureC_IStdcallGreeterVtbl *lpVtbl;

char *greeting;

int length;

};

/* naive attempt at porting a c++ class to C;

on x86, thiscall passes This via ecx register rather than

first argument; this register cannot be accessed in C without

inline assembly or calling a reinterpretation of byte array

as a function. there is no "This" argument in any of below. */

typedef struct pureC_CdeclGreeter pureC_CdeclGreeter;

typedef struct pureC_CdeclGreeterVtbl {

void (*dtor)(pureC_CdeclGreeter *This);

void (*setGreeting)(pureC_CdeclGreeter *This, const char *greeting);

void (*greet)(pureC_CdeclGreeter *This);

} pureC_CdeclGreeterVtbl;

struct pureC_CdeclGreeter {

pureC_CdeclGreeterVtbl *lpVtbl;

char *greeting;

int length;

};

void test() {

ICdeclGreeter *g = new CdeclGreeter;

g->setGreeting("hi");

g->greet();

IStdcallGreeter *g2 = new StdcallGreeter;

g2->setGreeting("hi");

g2->greet();

// we can pass pointers to our object to pure C using this interface,

// and it can still use it without doing anything to it.

pureC_StdcallGreeter *g3 = (pureC_StdcallGreeter *)g2;

g3->lpVtbl->setGreeting(g3, "hello, world!");

g3->lpVtbl->greet(g3);

g3->lpVtbl->dtor(g3);

free(g2);

/*

// cdecl passes this via ecx in x86, and not as the first argument;

// this means that this argument cannot be accessed in C without

// inline assembly or equivelent. Trying to run code below will cause a runtime error.

pureC_CdeclGreeter *g4 = (pureC_CdeclGreeter *)g;

g4->lpVtbl->setGreeting(g4, "hello, world!");

g4->lpVtbl->greet(g4);

g4->lpVtbl->dtor(g4);

free(g);

*/

delete g;

}

int main(int argc, char **argv)

{

test();

system("pause");

return 0;

}

TLDR;它不同于cdecl使得C++类在使用此约定的平台上不能从C使用，因为为了向方法发送“This”，您必须将ecx寄存器设置为“This”的地址，而不是仅仅推送它，并且同样如果你想要在C中实现一个C++可以识别的类，那么该方法需要从ecx寄存器中获取这个指针，C无法访问这个指针而没有内联装配或等效。

stdcall具有这个不错的属性，使用stdcall的类可以轻松地同时从C或C++使用，而无需对它们执行任何操作。

所以你只能#define __stdcall只要你不处理__thiscall;尽管可能还有其他一些细微的区别。