Python使用ctypes访问DLL函数- 使用函数*名称*失败

Question

myPythonClient（下面）希望调用ringBell函数（使用ctypes从DLL加载）。然而，试图通过其名称访问ringBell会导致AttributeError。为什么？

RingBell.h包含

namespace MyNamespace
    {
    class MyClass
        {
        public:
            static __declspec(dllexport) int ringBell ( void ) ;
        } ;
    }

RingBell.cpp包含

#include <iostream>
#include "RingBell.h"
namespace MyNamespace
    {
    int __cdecl MyClass::ringBell ( void )
        {
        std::cout << "\a" ;
        return 0 ;
        }
    }

myPythonClient.py包含

from ctypes import *
cdll.RingBell[1]() # this invocation works fine
cdll.RingBell.ringBell() # however, this invocation errors out
# AttributeError: function 'ringBell' not found

Answer 1

现在一切正常：）总结你的文章：

用C++编写DLL：

// Header
extern "C"
{   // Name in DLL will be "MyAdd" - but you won't be able to find parameters etc...
    __declspec(dllexport) int MyAdd(int a, int b);
}  
// Name will be with lot of prefixes but some other info is provided - IMHO better approach
__declspec(dllexport) int MyAdd2(int a, int b);

//.cpp Code
__declspec(dllexport) int MyAdd(int a, int b)
{   return a+b;
}
__declspec(dllexport) int MyAdd2(int a, int b)
{   return a+b;
} 

然后可以使用program link.exe查看dll中的实际函数名。 link.exe在MSVC2010中的示例如下：

c:\program files\microsoft visual studio 10.0\VC\bin\link.exe

使用：

link /dump /exports yourFileName.dll

你看到的是：

ordinal hint RVA      name
      1    0 00001040 ?MyAdd2@@YAHHH@Z = ?MyAdd2@@YAHHH@Z (int __cdecl MyAdd2(int,int))
      2    1 00001030 MyAdd = _MyAdd

然后在python中，您可以将其导入为：

import ctypes

mc = ctypes.CDLL('C:\\testDll3.dll')

#mc.MyAdd2(1,2) # this Won't Work - name is different in dll
myAdd2 = getattr(mc,"?MyAdd2@@YAHHH@Z") #to find name use: link.exe /dump /exports fileName.dll 
print myAdd2(1,2)
#p1 = ctypes.c_int (1) #use rather c types
print mc[1](2,3) # use indexing - can be provided using link.exe

print mc.MyAdd(4,5)
print mc[2](6,7) # use indexing - can be provided using link.exe