vs2008制作dll笔记，回带值样例-优快云博客

本文详细介绍了如何使用vs2008制作dll文件，包括创建dll文件、定义导出函数、编写cpp代码以及创建测试程序等步骤。通过实践操作，读者可以了解dll文件的制作流程，并掌握动态链接库的使用方法。

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使用vs2008制作dll文件，生成动态链接库，采用显示加载，以下记录实现过程：

1.制作dll文件

vs2008中，File > New Project > Other Language > Win32 > Win32 Console Application. 输入项目名称：MyDll。点击【OK】，【Next】，选择dll单选按钮，完成。
vs2008会自动生成一些代码，不用管它。创建MyDll.h，代码如下
MyDll.h 为了提高可用性，写了可回带值的函数供参考
Cpp代码
1. //MyDLL.h
2. extern "C" _declspec(dllexport) int Max(int a, int b);
3. extern "C" _declspec(dllexport) int Min(int a, int b);
4. extern "C" _declspec(dllexport) bool cim2scada(char* cimId, char** scadaId);
```
//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);
```
创建MyDll.cpp

Cpp代码

// MyDll.cpp : Defines the exported functions for the DLL application.
//
#include "stdafx.h"
#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) == 0){
printf("cimId无值！");
return false;
}
if(strcmp(cimId, "aaaaaa") == 0){
result = "1000";
}else if(strcmp(cimId, "bbbbbb") == 0){
result = "2000";
}
*scadaId = result;
printf("fun scadaId:%s\n", *scadaId);
return true;
}

// MyDll.cpp : Defines the exported functions for the DLL application.
//

#include "stdafx.h"
#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) == 0){
		printf("cimId无值！");
		return false;
	}

	if(strcmp(cimId, "aaaaaa") == 0){
		result = "1000";
	}else if(strcmp(cimId, "bbbbbb") == 0){
		result = "2000";
	}

	*scadaId = result;
	printf("fun scadaId:%s\n", *scadaId);
	return true;
}

编译一下，到工程的DEBUG目录，就可以找到MyDll.dll文件

2.创建测试程序

vs2008中，File > New Project > Other Language > Win32 > Win32 Console Application. 输入项目名称：DllTest。点击【OK】，【Next】，选择console单选按钮，去掉“预编译头”默认勾选项，完成。

Cpp代码

#include "windows.h"
#include <iostream>
void 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(5, 12);
char cimId[] = "aaaaaa";
char * scadaId = "";
bool b = cim2scada(cimId, &scadaId);
printf("Max结果为%d",a);
printf("cimId:%s, scadaId:%s", cimId, scadaId);
FreeLibrary(HDLL);//卸载MyDll.dll文件；
}

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

void 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(5, 12); 
	
	char cimId[] = "aaaaaa";
	char * scadaId = "";
	bool b = cim2scada(cimId, &scadaId);

	printf("Max结果为%d",a); 
	printf("cimId:%s, scadaId:%s", cimId, scadaId);
	FreeLibrary(HDLL);//卸载MyDll.dll文件； 
}

编译一下
拷贝MyDll.dll文件到DllTest项目的Debug目录下
打开一个控制台（cmd），进入DllTest > Debug目录，运行DllTest.exe
输出结果：
Cpp代码
1. fun scadaId : 1000
2. Max结果为12
3. cimId:aaaaaa, scadaId:1000
```
fun scadaId : 1000
Max结果为12
cimId:aaaaaa, scadaId:1000
```