c语言学习笔记 之调用dll动态库

项目基于vs2013

一、新建dll库项目

新建项目-->win32-->win32项目-->输入项目名-->选择Dll-->选择空项目-->完成

头文件如下

/*
下面定义了一套socket客户端发送报文接受报文的api接口
请写出这套接口api的调用方法
*/


#ifndef _INC_Demo01_H
#define _INC_Demo01_H


#ifdef  __cplusplus
extern "C" {
#endif
 
//客户端初始化 获取handle上下
int cltSocketInit(void **handle /*out*/); 

//客户端发报文
int cltSocketSend(void *handle /*in*/, unsigned char *buf /*in*/,  int buflen /*in*/);

//客户端收报文
int cltSocketRev(void *handle /*in*/, unsigned char *buf /*in*/, int *buflen /*in out*/);

//客户端释放资源
int cltSocketDestory(void *handle/*in*/);

#ifdef  __cplusplus
}
#endif


#endif  /* _INC_Demo01_H */

c文件：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct _SCK_HANDLE {
char version[16];
char    serverip[16];
int serverport;
unsigned char *buf ;
int buflen;
}SCK_HANDLE;






//客户端初始化 获取handle上下
__declspec(dllexport) 
int cltSocketInit(void **handle /*out*/)
{
int ret = 0;
SCK_HANDLE *sh = NULL;
sh = (SCK_HANDLE *)malloc(sizeof(SCK_HANDLE));
if (sh == NULL)
{
ret = -1;
printf("func cltSocketInit() err: %d, malloc err....", ret);
return ret;
}
memset(sh, 0, sizeof(SCK_HANDLE));
strcpy(sh->serverip, "192.168.0.128");
sh->serverport= 88;


*handle = sh;
return ret;
}


//客户端发报文
__declspec(dllexport) 
int cltSocketSend(void *handle /*in*/, unsigned char *buf /*in*/,  int buflen /*in*/)
{
int ret = 0;
SCK_HANDLE *sh = NULL; 

if (handle==NULL || buf==NULL)
{
ret = -1;
printf("func cltSocketSend() err: %d, (handle==NULL || buf==NULL)", ret);
return ret;
}
sh = (SCK_HANDLE *)handle ;
sh->buf = (char *)malloc(buflen);
if (sh->buf == NULL)
{
ret = -2;
printf("func cltSocketSend() err: %d, (buflen:%d)", ret, buflen);
return ret;
}
memcpy(sh->buf, buf, buflen);
sh->buflen = buflen;


return ret;
}




//客户端收报文
__declspec(dllexport) 
int cltSocketRev(void *handle /*in*/, unsigned char *buf /*in*/, int *buflen /*in out*/)
{
int  ret = 0;
SCK_HANDLE *sh = NULL; 


if (handle==NULL || buf==NULL || buflen==NULL)
{
ret = -1;
printf("func cltSocketSend() err: %d, ((handle==NULL || buf==NULL || buflen==NULL))", ret);
return ret;
}


sh = (SCK_HANDLE *)handle;


memcpy(buf, sh->buf, sh->buflen);
*buflen  = sh->buflen;


if (sh->buf != NULL)
{
free(sh->buf);
sh->buf = NULL; //把状态回到原始
sh->buflen = 0;
}
return ret;
}




//客户端释放资源
__declspec(dllexport) 
int cltSocketDestory(void *handle/*in*/)
{
int  ret = 0;
SCK_HANDLE *sh = NULL; 


if (handle==NULL )
{
ret = -1;
printf("func cltSocketSend() err: %d, ((handle==NULL )", ret);
return ret;
}


sh = (SCK_HANDLE *)handle;

if (sh->buf != NULL)
{
free(sh->buf);
sh->buf = NULL;
sh->buflen = 0;
}
free(sh);


return ret;
}

客户端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "socketclientdll.h"

void main()
{
int ret = 0;


void *handle = NULL;


unsigned char buf[1024]; /*in*/  
int buflen = 10;


unsigned char out[1024] = {0}; /*in*/
int outlen = 0;


strcpy(buf, "aadd3456789012233ddddddddddddddaaaaaaaaaaa");
//客户端初始化 获取handle上下
//运行的上下文环境 
ret = cltSocketInit(&handle/*out*/);
if (ret !=0)
{
printf("func cltSocketInit() err :%d \n", ret);
return ;
}


// //客户端发报文
ret = cltSocketSend(handle /*in*/, buf /*in*/,buflen /*in*/);
if (ret !=0)
{
printf("func cltSocketSend() err :%d \n", ret);
return ;
}
// 
// //客户端收报文
ret = cltSocketRev(handle /*in*/, out /*in*/, &outlen /*in out*/);
if (ret != 0)
{
printf("func cltSocketRev() err :%d \n", ret);
return ;
}
printf("out: %s \n", out);
// 
// //客户端释放资源
ret = cltSocketDestory(handle/*in*/);
if (ret != 0)
{
printf("func cltSocketDestory() err :%d \n", ret);
return ;
}


system("pause");
}