C++ DLL导出的两种方式和链接的两种方式

第一种 导出方式

extern "C" _declspec(dllexport) int Plus(int x, int y);
extern "C" _declspec(dllexport) int Sub(int x, int y);
extern "C" _declspec(dllexport) int Mul(int x, int y);
extern "C" _declspec(dllexport) int Div(int x, int y);

int Plus(int x, int y)
{
    return x + y;
}

int Sub(int x, int y)
{
    return x - y;
}

int Mul(int x, int y)
{
    return x * y;
}

int Div(int x, int y)
{
    return x / y;
}

第二种 导出方式

在项目上添加一个def文件

// def文件里面
EXPORTS
Plus @12
Sub @17
Mul @15 NONAME   // (此种方式只导出序号)
Div @16

// CPP文件里面
int Plus(int x, int y)
{
    return x + y;
}

int Sub(int x, int y)
{
    return x - y;
}

int Mul(int x, int y)
{
    return x * y;
}

int Div(int x, int y)
{
    return x / y;
}

DLL使用

第一种 隐式链接

// 先把TestDll.lib 和 TestDll.dll放在main.cpp 同一目录下
#include <stdio.h>
#pragma comment(lib, "TestDll.lib")

extern "C" _declspec(dllimport) int Plus(int x, int y);
extern "C" _declspec(dllimport) int Sub(int x, int y);
extern "C" _declspec(dllimport) int Mul(int x, int y);
extern "C" _declspec(dllimport) int Div(int x, int y);

int main()
{
    int d = Plus(2, 3);
    printf("%d", d);
    getchar();
    return 0;
}

第二种 显示链接

#include <stdio.h>
#include <windows.h>

int main()
{
    // 定义函数指针
    typedef int(*lpPlus)(int, int);
    typedef int(*lpSub)(int, int);
    typedef int(*lpMul)(int, int);
    typedef int(*lpDiv)(int, int);
    // 获取模块句柄
    HMODULE hMoudle = LoadLibrary(L"TestDll.dll");
    // 获取函数地址
    lpPlus MyPlus = (lpPlus)GetProcAddress(hMoudle, "Plus");
    lpSub MySub = (lpSub)GetProcAddress(hMoudle, "Sub");
    lpMul MyMul = (lpMul)GetProcAddress(hMoudle, "Mul");
    lpDiv Mydiv = (lpDiv)GetProcAddress(hMoudle, "Div");
    // 调用
    int d = MyPlus(2, 3);
    printf("%d", d);
    getchar();
    return 0;
}