VC中创建DLL，导出全局变量，函数和类

一.创建DLL

1.在VC中新建一个Win32空项目MathLib；

2.添加预编译头文件stdafx.h，定义导入导出控制符号：

  1: //stdafx.h
  2: #pragma once
  3: #define MATHLIB_EXPORT

3.添加包含要导出的全局变量,函数和类的头文件MathLib.h:

  1: //MathLib.h
  2: #pragma once
  3: 
  4: #ifdef MATHLIB_EXPORT
  5: #define MATHLIBAPI __declspec(dllexport)
  6: #else
  7: #define MATHLIBAPI __declspec(dllimport)
  8: #endif
  9: 
 10: //macro
 11: #define PI 3.14149
 12: 
 13: //Global variable
 14: extern MATHLIBAPI int GlobalVariable;
 15: 
 16: //Function
 17: MATHLIBAPI int Add(int a,int b);
 18: 
 19: //Class
 20: class MATHLIBAPI Math
 21: {
 22: public:
 23: 	int Multiply(int a,int b);
 24: };

4.添加所导出元素的实现文件MathLib.cpp

  1: //MathLib.cpp
  2: #include "stdafx.h"
  3: #include "MathLib.h"
  4: 
  5: int GlobalVariable = 100;
  6: 
  7: int Add(int a,int b)
  8: {
  9: 	return a+b;
 10: }
 11: 
 12: int Math::Multiply(int a,int b)
 13: {
 14: 	return a*b;
 15: }

二,测试所创建的DLL

测试代码:

  1: #include "stdafx.h"
  2: #include <iostream>
  3: using namespace std;
  4: 
  5: #include "../MathLib/MathLib.h"
  6: #pragma comment(lib,"../Debug/MathLib.lib")
  7: 
  8: int _tmain(int argc, _TCHAR* argv[])
  9: {
 10: 	cout<<"Pi = "<<PI<<endl;
 11: 
 12: 	cout<<"GlobalVariable = "<<GlobalVariable<<endl;
 13: 
 14: 	int a = 20,b = 30;
 15: 	cout<<"a="<<a<<", "<<"b="<<b<<endl;
 16: 	cout<<"a+b = "<<Add(a,b)<<endl;
 17: 
 18: 	Math math;
 19: 	cout<<"a*b = "<<math.Multiply(a,b)<<endl;
 20: 
 21: 	return 0;
 22: }