问题描述
此C ++函数的正确VB6声明是什么？
What is the correct VB6 declaration for this C++ function?
LPCWSTR* MW_ListReaders(_ULONG Context, int* NumberOfReaders);
以下内容为我提供了错误的DLL调用约定：
The following gave me "Bad DLL calling convention":
Private Declare Function ListReaders Lib "MyDLL.dll" (ByVal Context As Long, _
ByRef NumberOfReaders As Integer) As Long
推荐答案
在该C ++声明中未指定调用约定。大多数C / C ++编译器默认为 __ cdecl 。如果该函数确实使用 __ cdecl ，则您将无法在VB6中调用它：
There is no calling convention specified in that C++ declaration. Most C/C++ compilers default to __cdecl. If the function does actually use __cdecl then you will not be able to call it in VB6:
注意：在Visual Basic中创建的.EXE文件将允许您调用已用_cdecl调用约定声明的DLL函数，而不会发生错误。只有当您尝试从Visual Basic IDE运行程序时调用此类函数时，Visual Basic才会生成以下错误：
NOTE: An .EXE file created in Visual Basic will allow you to call a DLL function that has been declared with the _cdecl calling convention without an error. It is only when you try to call such a function when running a program from the Visual Basic IDE, that Visual Basic generates the following error:
运行时错误'49 '：
错误的DLL调用约定
Run-time Error '49': Bad DLL Calling Convention
EXE版本允许您调用此类函数的事实已被Microsoft确认为错误。您不应该依赖此行为，因为在Visual Basic的将来版本中这可能会更改。
The fact that the EXE version allows you to call such functions has been confirmed to be a bug by Microsoft. You should not rely on this behavior as this might change in future versions of Visual Basic.
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