动态链接库DLL导出函数并导入使用
本文完全参考自《vs2008制作dll笔记，回带值样例》。
首先制作DLL文件，在vs2010中新建Win32控制台项目，选择DLL选项，简历头文件，源文件如下：
头文件：
// MyDll.h
extern "C" _declspec(dllexport) int Max(int a, int b);
extern "C" _declspec(dllexport) int Min(int a, int b);
extern "C" _declspec(dllexport) bool cim2scada(char* cimId, char** scadaId);
源文件：
// MyDll.cpp : Defines the exported functions for the DLL application.
// #include "MyDll.h"
#include <iostream> int Max(int a, int b)
{
if (a >= b)
{
return a;
}
else
{
return b;
}
} int Min(int a, int b)
{
if (a >= b)
{
return b;
}
else
{
return a;
}
} bool cim2scada(char* cimId, char** scadaId)
{
char* result;
if (cimId == NULL)
{
printf("空指针！");
return false;
}
else if (strlen(cimId) == )
{
printf("cimId无值！");
return false;
} if (strcmp(cimId, "aaaaaa") == )
{
result = "";
}
else if (strcmp(cimId, "bbbbbb"))
{
result = "";
} *scadaId = result;
printf("fun scadaId: %s \n", *scadaId);
return true;
}
然后，创建测试样例，重新简历Win32控制台程序，选择控制台选项，建立测试代码：
#include "windows.h"
#include <iostream> int main()
{
typedef int (*pMax)(int a, int b);
typedef int (*pMin)(int a, int b);
typedef bool (*pcim2scada)(char* cimid, char** scada); HINSTANCE HDLL;
HDLL = LoadLibrary(L"MyDll.dll"); // 加载动态链接库MyDll.dll文件；
pMax Max = (pMax)GetProcAddress(HDLL, "Max");
pMin Min = (pMin)GetProcAddress(HDLL, "Min");
pcim2scada cim2scada = (pcim2scada)GetProcAddress(HDLL, "cim2scada"); int a = Max(, );
char* cimId = "aaaaaa";
char* scadaId = "";
bool b = cim2scada(cimId, &scadaId); printf("Max结果为%d\n", a);
printf("cimId:%s, scadaId:%s\n", cimId, scadaId); FreeLibrary(HDLL); // 卸载MyDll.dll文件
}
编译生成Debug文件夹，讲之前生成的Dll文件拷贝到该Debug文件夹中，然后运行该测试样例。
DLL导出并导入生成函数需要注意几点：
extern "C" _declspec(dllexport)
typedef int (*pMax)(int a, int b);
typedef int (*pMin)(int a, int b);
typedef bool (*pcim2scada)(char* cimid, char** scada);
HINSTANCE HDLL;
HDLL = LoadLibrary(L"MyDll.dll"); // 加载动态链接库MyDll.dll文件；
pMax Max = (pMax)GetProcAddress(HDLL, "Max");
pMin Min = (pMin)GetProcAddress(HDLL, "Min");
pcim2scada cim2scada = (pcim2scada)GetProcAddress(HDLL, "cim2scada");
接下来，将学习如何用DLL导出C++类、对象，并进行导入使用。