python 调用dll python 调用dll找不到函数

在工作中遇到了一个python调用c的dll，最先尝试用ctype的windll和dll的方法去调用，都显示没有找到dll下的函数：

from ctypes import *


def load_dll():
    return WinDLL('Api5040S')


def read_power():
    print(load_dll().fnGetPowerValue)


if __name__ == '__main__':
    read_power()

Traceback (most recent call last):
  File "D:/Ptpythonworkspace/pythonProject2/Dome2.py", line 18, in <module>
    read_power()
  File "D:/Ptpythonworkspace/pythonProject2/Dome2.py", line 14, in read_power
    print(load_dll().fnGetPowerValue)
  File "D:\py37-32\lib\ctypes\__init__.py", line 369, in __getattr__
    func = self.__getitem__(name)
  File "D:\py37-32\lib\ctypes\__init__.py", line 374, in __getitem__
    func = self._FuncPtr((name_or_ordinal, self))
AttributeError: function 'fnGetPowerValue' not found

百度了好久发现是因为：

客户也不愿意去更改dll，在绞尽脑汁之后，想了一个曲线救国的方法，用c#去调用c的dll，然后生成一个新的dll给python调用:

现在visual studio中写了一个调用c的dll的方法实验一下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using Api5040S_NameSpace;

namespace ConsoleApp5
{
    public class GetPowerValue
    {
        static void Main(string[] args)
        {
            Api5040S_NameSpace.Api5040S CallDll = new Api5040S_NameSpace.Api5040S();
            string strErr = "";
            float fPower = -45;
            int iPort = Convert.ToInt32(1);
            Console.Write(CallDll.fnGetPowerValue(1, "192.168.100.3", ref strErr, ref fPower, 2437, "192.168.100.254"));
            Console.Write(fPower);
            Console.ReadKey();
        }
    }
    
}

运行成功了：

接下来就需要把c#的调用生成一个dll，代码如下：ReadApi5040S.dll

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Api5040S_NameSpace;

namespace ReadApi5040S
{
    public class Program
    {

        public static Tuple<string,float> GetPowerValue(int iPort, string strIp, ref string strErr, ref float fPower, int Frequency, string strRemoteIp = "192.168.100.254")
        {
            Api5040S_NameSpace.Api5040S CallDll = new Api5040S_NameSpace.Api5040S();
            iPort = Convert.ToInt32(iPort);
            strIp = strIp;
            strErr = strErr;
            fPower = -45;
            Frequency = Frequency;
            strRemoteIp = strRemoteIp;
            int result = CallDll.fnGetPowerValue(iPort, strIp, ref strErr, ref fPower, Frequency, strRemoteIp = "192.168.100.254");
            return Tuple.Create(strErr,fPower);
        }
    }
}

这样就能用python去调用里面封装的方法了。
接下来就是python调用c#的dll：
先安装pythonnet的安装包

pip install pythonnet

下面调用代码给上：

import clr

clr.AddReference("ReadApi5040S")
from ReadApi5040S import *
instance = Program()


def ReadPower():
    iPort = 2
    strIp = '192.168.100.3'
    strErr = ''
    fPower = 2
    Frequency = 5500
    strRemoteIp = '192.168.100.254'
    return instance.GetPowerValue(iPort, strIp, strErr, fPower, Frequency, strRemoteIp)[2]


if __name__ == '__main__':
    print(ReadPower())

运行结果：

D:\py37-32\python.exe D:/Ptpythonworkspace/pythonProject2/Demo.py
-90.0

Process finished with exit code 0

ok了，曲线救国成功了