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分享急。。急：一个有关截获API函数的问题
我在一个钩子DLL中实现了对API函数--MessageBoxA()的截获；如果我把自己的MessageBoxA函数－－MyMessageBoxA()的调用约定定义为__cdecl，即
int __cdecl MyMessageBoxA(HWND hWnd,LPCSTR lpText,LPCSTR lpCaption,UINT uType)，则会报错“Access violation at address 00000000.Read of address 00000000”;而如果将MyMessageBoxA()的调用约定定义为__stdcall，即
int __stdcall MyMessageBoxA(HWND hWnd,LPCSTR lpText,LPCSTR lpCaption,UINT uType),则不会报错。
请问为什么？
int __cdecl MyMessageBoxA(HWND hWnd,LPCSTR lpText,LPCSTR lpCaption,UINT uType)，则会报错“Access violation at address 00000000.Read of address 00000000”;而如果将MyMessageBoxA()的调用约定定义为__stdcall，即
int __stdcall MyMessageBoxA(HWND hWnd,LPCSTR lpText,LPCSTR lpCaption,UINT uType),则不会报错。
请问为什么？
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888888888888 2003-06-13
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同意楼上
Purple_Z 2003-06-13
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这两种调用的压栈方式不同的，即参数压入的顺序有所不同，另外还有一些其他的小差别
nnfish 2003-06-12
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在dll中用不同的调用方式声明的函数，是要用不同的调用方式来调用，否则就出错。
例如Win32 API就应该用__stdcall方式来调用呀，，呵呵
例如Win32 API就应该用__stdcall方式来调用呀，，呵呵
nnfish 2003-06-12
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以下是delhpi的在线帮助：
The table below summarizes calling conventions.
Directive Parameter order Clean-up Passes parameters in registers?
register Left-to-right Routine Yes
pascal Left-to-right Routine No
cdecl Right-to-left Caller No
stdcall Right-to-left Routine No
safecall Right-to-left Routine No
The default register convention is the most efficient, since it usually avoids creation of a stack frame. (Access methods for published properties must use register.)
The cdecl convention is useful when you call functions from DLLs written in C or C++, while stdcall and safecall are used for Windows API calls.
The safecall convention must be used for declaring dual-interface methods.
The pascal convention is maintained for backward compatibility.
明白了吧，呵呵：）
The table below summarizes calling conventions.
Directive Parameter order Clean-up Passes parameters in registers?
register Left-to-right Routine Yes
pascal Left-to-right Routine No
cdecl Right-to-left Caller No
stdcall Right-to-left Routine No
safecall Right-to-left Routine No
The default register convention is the most efficient, since it usually avoids creation of a stack frame. (Access methods for published properties must use register.)
The cdecl convention is useful when you call functions from DLLs written in C or C++, while stdcall and safecall are used for Windows API calls.
The safecall convention must be used for declaring dual-interface methods.
The pascal convention is maintained for backward compatibility.
明白了吧，呵呵：）
