利用函数指针实现C的回调函数，实现调用者和底层驱动的解耦
【摘要】
新建空项目，命名为RF_Drive,这个作为底层的驱动。
添加MyDrive.c文件，向文件中添加代码，模拟驱动一些函数，代码如下：
思路：
EncData和DecData实现信息的加密和解密，由于不同厂家的设备，加密和解密的方式不同，所以不能在底层驱动中实现，需要不同的厂家在自己的函数库中实现。厂家和驱动约定好相...
- 新建空项目，命名为RF_Drive,这个作为底层的驱动。
- 添加MyDrive.c文件，向文件中添加代码，模拟驱动一些函数，代码如下：
思路：
EncData和DecData实现信息的加密和解密，由于不同厂家的设备，加密和解密的方式不同，所以不能在底层驱动中实现，需要不同的厂家在自己的函数库中实现。厂家和驱动约定好相同的接口，将函数通过指针传进来，实现函数的回调。
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#define _CRT_SECURE_NO_WARNINGS
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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//完成发送报文的时候,进行数据加密
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//定义函数指针类型 通过函数指针类型 来约定 厂商 去实现 加密解密函数的原型
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typedef int(*EncData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
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typedef int(*DecData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
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typedef struct _Sck_Handle
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{
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char version[16];
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char ip[16];
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int port;
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unsigned char *p;
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int len;
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char *p2;
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}Sck_Handle;
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int socketclient_sendAndEnc1(void *handle, unsigned char *buf, int buflen, EncData encDataCallback)
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{
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int ret = 0;
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unsigned char cryptbuf[4096];
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int cryptbuflen = 4096;
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Sck_Handle *tmpHandle = NULL;
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if (handle == NULL || buf == NULL || encDataCallback == NULL)
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{
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ret = -1;
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printf("func socketclient_sendAndEnc1() err :%d check handle == NULL err \n", ret);
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return ret;
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}
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ret = encDataCallback(buf, buflen, cryptbuf, &cryptbuflen); //间接的调用子任务
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if (ret != 0)
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{
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ret = -2;
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printf("func socketclient_sendAndEnc1() err :%d check handle == NULL err \n", ret);
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return ret;
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}
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tmpHandle = (Sck_Handle *)handle;
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tmpHandle->len = cryptbuflen;
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tmpHandle->p = (unsigned char *)malloc(cryptbuflen);
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if (tmpHandle->p == NULL)
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{
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ret = -3;
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printf("func socketclient_sendAndEnc1() err :%d mallocerr \n", ret);
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return ret;
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}
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//把加密的明文 缓存到 内存中
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memcpy(tmpHandle->p, cryptbuf, cryptbuflen);
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return 0;
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}
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//socket客户端环境初始化
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int socketclient_init(void **handle)
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{
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int ret = 0;
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Sck_Handle *tmpHandle = NULL;
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if (handle == NULL)
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{
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ret = -1;
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printf("func socketclient_init() err :%d check handle == NULL err \n", ret);
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return ret;
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}
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tmpHandle = (Sck_Handle *)malloc(sizeof(Sck_Handle));
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if (tmpHandle == NULL)
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{
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ret = -2;
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printf("func socketclient_init() err :%d malloc err \n", ret);
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return ret;
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}
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memset(tmpHandle, 0, sizeof(Sck_Handle));
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strcpy(tmpHandle->version, "1.0.0.1");
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strcpy(tmpHandle->ip, "192.168.12.12");
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tmpHandle->port = 8081;
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//间接赋值
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*handle = tmpHandle;
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return ret;
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}
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//socket报文发送
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int socketclient_send(void *handle, unsigned char *buf, int buflen)
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{
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int ret = 0;
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Sck_Handle *tmpHandle = NULL;
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if (handle == NULL || buf == NULL || buflen <= 0)
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{
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ret = -2;
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printf("func socketclient_send() err :%d (handle == NULL || buf==NULL || buflen <=0 ) \n", ret);
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return ret;
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}
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tmpHandle = (Sck_Handle *)handle;
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tmpHandle->len = buflen;
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tmpHandle->p = (unsigned char *)malloc(buflen);
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if (tmpHandle->p == NULL)
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{
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ret = -2;
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printf("func socketclient_send() err :%d malloc len:%d \n", ret, buflen);
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return ret;
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}
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memcpy(tmpHandle->p, buf, buflen); //数据的缓存到内存
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return ret;
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}
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//socket报文接受
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int socketclient_recv(void *handle, unsigned char *buf, int *buflen)
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{
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int ret = 0;
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Sck_Handle *tmpHandle = NULL;
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if (handle == NULL || buf == NULL || buflen == NULL)
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{
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ret = -2;
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printf("func socketclient_recv() err :%d (handle == NULL || buf==NULL || buflen==NULL ) \n", ret);
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return ret;
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}
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tmpHandle = (Sck_Handle *)handle;
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memcpy(buf, tmpHandle->p, tmpHandle->len);
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*buflen = tmpHandle->len; //间接赋值 告诉调用者 收到的数据的长度
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return ret;
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}
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//socket环境释放
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int socketclient_destory(void *handle)
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{
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int ret = 0;
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Sck_Handle *tmpHandle = NULL;
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if (handle == NULL)
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{
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return -1;
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}
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tmpHandle = (Sck_Handle *)handle;
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if (tmpHandle->p != NULL)
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{
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free(tmpHandle->p); //释放结构体 成员域的 指针所指向的内存空间
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}
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free(tmpHandle); //释放结构体内存
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return 0;
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}
- 添加MyDrive.h文件。
完成后，右键项目，将配置类型改为dll动态链接库。
- 新建TestDrive工程，测试底层dll。将生成的RF_Drive.dll、RF_Drive.lib和MyDrive.h文件放到工程目录下面。
- 将RF_Drive链接到TestDrive。选择输入，然后选择附加依赖项，将RF_Drive.lib添加进去，然后点击确定。
- 将MyDrive.h包含到项目，然后新建Test.c文件，在Test.c中写入测试代码。代码如下：
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#ifndef _INC_MYDRIVE_H__
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#define _INC_MYDRIVE_H__
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#define Import_SSS
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#ifdef Import_SSS
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#define API _declspec(dllexport)
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#else
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#define API _declspec(dllimport)
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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//1 数据类型的封装
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//2 handle的概念: 底层库的内存资源,记录着函数运行的上下文信息..
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//3 底层库提供的是一种机制, 而不是满足某一个人的策略
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//完成发送报文的时候,进行数据加密
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//定义函数指针类型 通过函数指针类型 来约定 厂商 去实现 加密解密函数的原型
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typedef int(*EncData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
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typedef int(*DecData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
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API
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int socketclient_init(void **handle);
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API
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int socketclient_send(void *handle, unsigned char *buf, int buflen);
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API
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int socketclient_sendAndEnc1(void *handle, unsigned char *buf, int buflen, EncData encDataCallback);
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API
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int socketclient_recv(void *handle, unsigned char *buf, int *buflen);
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API
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int socketclient_destory(void *handle);
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#ifdef __cplusplus
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}
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#endif
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#endif
思路：
在调用者实现加密算法Hw_EncData，不同的调用者，实现加密算法的方式不同，需要调用者自己实现，然后将函数的指针传递给底层驱动。
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#define _CRT_SECURE_NO_WARNINGS
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "MyDrive.h"
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int Hw_EncData(unsigned char *in, int inlen, unsigned char *out, int *outlen)
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{
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printf("func Hw_EncData begin....\n ");
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strcpy((char *)out, "123456789");
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*outlen = 9;
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printf("func Hw_EncData end....\n ");
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return 0;
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}
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void main()
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{
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unsigned char buf[1024];
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int buflen;
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unsigned char out[1024];
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int outlen;
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void *handle = NULL;
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int ret = 0;
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strcpy((char *)buf, "aaaaaaaaaffffffffdddddddd");
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buflen = 9;
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//客户端初始化 获取handle上下
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ret = socketclient_init(&handle /*out*/);
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if (ret != 0)
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{
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printf("func socketclient_init() err:%d \n ", ret);
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goto End;
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}
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//客户端发报文
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//ret = socketclient_send(handle /*in*/, buf /*in*/, buflen /*in*/);
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ret = socketclient_sendAndEnc1(handle, buf, buflen, Hw_EncData);
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if (ret != 0)
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{
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printf("func socketclient_send() err:%d \n ", ret);
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goto End;
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}
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//客户端收报文
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ret = socketclient_recv(handle /*in*/, out /*in*/, &outlen/*in out*/);
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if (ret != 0)
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{
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printf("func socketclient_recv() err:%d \n ", ret);
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goto End;
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}
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End:
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//客户端释放资源
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ret = socketclient_destory(handle/*in*/);
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printf("hello...\n");
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system("pause");
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printf("hello...\n");
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system("pause");
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return;
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}
运行结果如下：
代码：https://download.csdn.net/download/hhhhhhhhhhwwwwwwwwww/12898322
文章来源: wanghao.blog.csdn.net，作者：AI浩，版权归原作者所有，如需转载，请联系作者。
原文链接：wanghao.blog.csdn.net/article/details/108870746
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