cmake 编译 c++ dll 的一个例子(更新2：增加 python 调用方法)

CMakeLists.txt

project(xxx)
add_library(xxx SHARED xxx.cpp)
add_executable(yyy yyy.cpp)
target_link_libraries(yyy xxx)

xxx.h

#ifndef XXX_XXX_H
#define XXX_XXX_H
#endif

#pragma once
#ifdef BUILD_XXX_DLL
#define IO_XXX_DLL __declspec(export)
#else
#define IO_XXX_DLL __declspec(import)
#endif

extern "C"
{
IO_XXX_DLL void hello(void);
IO_XXX_DLL double sum(double a, double b);
}

xxx.cpp

#define BUILD_XXX_DLL

#include "xxx.h"
#include <iostream>

using namespace std;

IO_XXX_DLL void hello(void)
{
    cout<<"Hello from dll!\n"<<endl;
}

IO_XXX_DLL double sum(double a, double b)
{
    cout<<"The sum of "<<a<<" and "<<b<<" is: "<<a + b<<endl;
    return a + b;
}

yyy.cpp

#include <windows.h>
#include <iostream>

using namespace std;

int main()
{
    HINSTANCE h = LoadLibrary("C:\\Users\\Perelman\\.CLion2016.1\\system\\cmake\\generated\\xxx-4d5c076f\\4d5c076f\\Debug\\libxxx.dll");
    typedef void (*p0)(void);
    p0 hello = (p0)GetProcAddress(h, "hello");
    cout<<"Run hello:\n"<<endl;
    hello();
    typedef double (*p1)(double, double);
    p1 sum = (p1)GetProcAddress(h, "sum");
    cout<<"Run sum:\n"<<endl;
    sum(10.0, 12.0);
    FreeLibrary(h);
    return 0;
}

yyy.py

import ctypes
# 注意一，注意 64bit 32bit 的问题，如果出现 193 错误：%1 不是有效的Win32应用程序，则见编译器由 64bit 更换为 32bit 即可
# 注意二，由于 dll 里是 cdecl 接口（如 extern “C” __declspec(dllimport)），因此 python 里用 ctypes.CDLL 接口
h = ctypes.CDLL('C:\\Users\\Perelman\\.CLion2016.1\\system\\cmake\\generated\\xxx-4d5c076f\\4d5c076f\\Debug\\libxxx.dll')
h.hello()
# 注意三，python 里的数据要经过 ctypes 处理下
# 指明参数格式
h.sum.argtypes = (ctypes.c_double, ctypes.c_double)
# 指明返回格式
h.sum.restype = ctypes.c_double
print(h.sum(10.1, 3))