程序代码：

#ifdef _LIB
#ifndef HELLOWORLD_API
#define HELLOWORLD_API extern
#define    HELLOWORLDLIB_API extern
#pragma message("LIB")
#endif
#endif

#ifdef _USRDLL
#ifdef HELLOWORLDLIBDLL_EXPORTS
#define HELLOWORLD_API extern  __declspec(dllexport)
#define HELLOWORLDLIB_API extern __declspec(dllexport)
#pragma message("Create HELLOWORLD dllexport")
#else
#define HELLOWORLD_API extern __declspec(dllimport)
#define HELLOWORLDLIB_API extern __declspec(dllimport)
#pragma message("Using HELLOWORLD dllexport")
#endif
#endif

#ifdef __cplusplus
extern "C" {
#endif 

    HELLOWORLD_API void print();
    HELLOWORLD_API int add(int a, int b);

#ifdef __cplusplus
}
#endif 

程序代码：

#include <stdio.h>
#include "HelloWorldDll.h"

int main()
{
    print();
    int c = add(1, 2);
    return 0;
}

/*
void print()
{
    printf("hello world");
}

int add(int a, int b)
{
    return a+b;
}
*/