使用方法声明“_Something”在 VBA(Excel) 中导入 C++ dll
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C++ dll import in VBA(Excel) with a method declaration "_Something"
提问by Bongo
I am having some problems with a c++ dll i recently got from a friend. I am trying to import the dll into an Excel VBA Add-in. (I am using Excel 2010 32bit and the dll is compiled in Visual Studio 2008)
我最近从朋友那里得到的 c++ dll 有一些问题。我正在尝试将 dll 导入 Excel VBA 插件。（我使用的是 Excel 2010 32bit 并且 dll 是在 Visual Studio 2008 中编译的）
First of all i tried to import it but it failed with a runtime error 49. I concluded that it possibly comes from a missing c++ declaration (__stdcal). (i thought visual studio should do this automatically but okay)
首先，我尝试导入它，但它因运行时错误 49 而失败。我得出结论，它可能来自缺少 c++ 声明 (__stdcal)。（我认为 Visual Studio 应该自动执行此操作，但还可以）
Now i have a new dll with __stdcal in its declaration, but the methods are declared with a underscore ( _ ) at its beginning.
现在我有一个在声明中带有 __stdcal 的新 dll，但是这些方法在其开头用下划线 ( _ ) 声明。
So when i try to declare the Sub, Excel tells me something like "invalid character" is there a possibility to avoid this without altering the c++ files ?
因此，当我尝试声明 Sub 时，Excel 会告诉我诸如“无效字符”之类的内容，是否有可能在不更改 C++ 文件的情况下避免这种情况？
'void _SaveFile(const char *FileName_);'
Declare Sub _SaveFile Lib "D:/DLL/TableController.dll" (ByRef FileName_ As String)
^
|
Thanks in advance
提前致谢
Here are some additional informations which maybe lead to a solution for my problems.
这里有一些额外的信息，可能会导致我的问题的解决方案。
I got now some c++ code to debug my problem... I still get the runtime error 49 but the dependency walker gives me now the right names of the methods( which is pretty awesome i think ;) )
我现在得到了一些 C++ 代码来调试我的问题......我仍然得到运行时错误 49 但依赖walker现在给了我正确的方法名称（我认为这非常棒；））
I tried to use the same dll in an C# program. As i expected it worked perfectly normal. Here is my C# code this is the import:
我试图在 C# 程序中使用相同的 dll。正如我所料，它完全正常。这是我的 C# 代码，这是导入：
[DllImport("JLTable.dll",CallingConvention=CallingConvention.StdCall)]
internal static extern void JLReadFile(string _FileName);
[DllImport("JLTable.dll", CallingConvention = CallingConvention.StdCall)]
internal static extern long JLGetRowCount();
annd this happens if i click a Button
如果我点击一个按钮就会发生这种情况
TableRunner.JLReadFile(@"D:\file.tab");
long rows = TableRunner.JLGetRowCount();
MessageBox.Show(rows.ToString());
Here is my code in VBA The declaration:
这是我在 VBA 中的代码声明：
Declare Function JLReadFile Lib "D:/JLTable.dll" (ByRef FileName_ As String)
Declare Function JLGetRowCount Lib "D:/JLTable.dll" () As Long
And the call:
和电话：
Sub Read()
Dim path As String
path = "D:/file.tab"
JLReadFile (path)
Dim count As Long
count = JLGetRowCount()
End Sub
And Here is also the c++ code i want to call. Because of some reason my friend doesn't want me to show what the code exactly does but it still behaves the same way with this code.
这也是我想调用的 c++ 代码。由于某种原因，我的朋友不希望我展示代码的确切功能，但它仍然以与此代码相同的方式运行。
The .h file(the JLTable_API is something like #define JLTable_API __declspec(dllexport))
.h 文件（JLTable_API 类似于 #define JLTable_API __declspec(dllexport)）
#define STDCALL
extern "C"
{
JLTABLE_API void STDCALL JLReadFile(const char *FileName_);
JLTABLE_API void STDCALL JLSaveFile(const char *FileName_);
}
The .c++ file
.c++ 文件
void STDCALL JLReadFile(const char *FileName_)
{
//log something to a file
}
long STDCALL JLGetRowCount()
{
//log something to a file
return 0;
}
I am very grateful for every hint you can give me
我非常感谢你能给我的每一个提示
And as always Thanks in advance
和往常一样提前致谢
回答by Bongo
I finally have a solution. i found a blog which showed me what i did wrong.
我终于有了解决方案。我找到了一个博客，它告诉我我做错了什么。
As described you need the correct method name, to figure out which is the correct one i used the dependency walker. This finally led me to this declaration
如上所述，您需要正确的方法名称，以确定哪个是我使用依赖项walker 的正确方法。这最终使我做出了这个声明
VBA:
VBA：
Declare Sub JLReadFile Lib "D:/JLTable.dll" (ByRef FileName_ As String) Alias "_JLReadFile@4" (ByRef FileName_ As String)
C++:
C++：
void __declspec (dllexport) _stdcall JLReadFile(const char *FileName_);
回答by M4rc
From a similar test I ran, you need to use the "Alias" keyword. So that it would be written similar to: Declare Sub SaveFile Lib "D:/DLL/TableController.dll" Alias "_SaveFile" (ByRef FileName_ As String)
在我运行的类似测试中，您需要使用“别名”关键字。所以它会写成类似于：Declare Sub SaveFile Lib "D:/DLL/TableController.dll" Alias "_SaveFile" (ByRef FileName_ As String)
Additionally, I don't think you have to pass filename by reference, but I could be wrong. It's been a while since I've used VB. More information on importing functions from a dynamic library, check thispage out
此外，我认为您不必通过引用传递文件名，但我可能是错的。我已经有一段时间没有使用 VB 了。有关从动态库导入函数的更多信息，请查看此页面
