C 语言回调函数客户端简单示例
C 语言回调函数客户端简单示例回调函数就是一个被作为参数传递的函数。在C语言中，回调函数只能使用函数指针实现，在C++、Python、ECMAScript等更现代的编程语言中还可以使用仿函数或匿名函数。回调函数的使用可以大大提升编程的效率，这使得它在现代编程中被非常多地使用。同时，有一些需求必须要使用回调函数来实现。使用回调函数就会让别的程序员调用我们的代码时操作简单。client.h：
#ifndef _HY_TCP_H
#define _HY_TCP_H
typedef void (* recv_callback)(char *data, int len);//定义回调
typedef struct param{
recv_callback callback;
} callback_param;
int tcp_dns_change(char *dns, char *str, int size);
int tcp_connect(char *IP,int PORT);
void tcp_disconnect(void);
int tcp_send(char *buf);
int tcp_recv(char *buf, int size);
void *thread_recv(void *param);
void tcp_register_callback(recv_callback cb); //调用回调函数
#endif
client.c：
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <netdb.h>
#include <syslog.h>
#include <pthread.h>
#include <poll.h>
#include "hy_tcp.h"
int sockfd;
enum {
STATE_NOCONNECTED,//未连接
STATE_CONNECTED, //已连接
STATE_DISCONNECTE //连接断开
};
int connect_state = STATE_NOCONNECTED;
int tcp_dns_change(char *dns, char *str, int size)
{
struct hostent *hptr;
hptr = gethostbyname(dns);
if (hptr == NULL) {
syslog(LOG_ERR, "gethostbyname error");
return -1;
}
syslog(LOG_INFO, "ipaddr:%s\n", inet_ntop(hptr->h_addrtype, hptr->h_addr, str, size));
return 0;
}
int tcp_connect(char *IP,int PORT)
{
if (connect_state == STATE_NOCONNECTED) {
struct sockaddr_in server_addr;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
syslog(LOG_ERR, "create socket failed!\n");
return -1;
}
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(PORT);
server_addr.sin_addr.s_addr = inet_addr(IP);
if (connect(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
syslog(LOG_ERR, "connet error!\n");
return -1;
}
connect_state = STATE_CONNECTED;
syslog(LOG_INFO, "connect success!\n");
return 0;
}
else
return -1;
}
void tcp_disconnect(void)
{
if (connect_state != STATE_NOCONNECTED) {
close(sockfd);
syslog(LOG_INFO, "connect is break!\n");
}
}
int tcp_send(char *buf)
{
if (connect_state == STATE_CONNECTED) {
return send(sockfd, buf, strlen(buf)+1, 0);
}
else
return -1;
}
void *thread_recv(void *param)
{
int ret;
static char buf = {0};
char heartbeat_buf[] = "heartbeat data";
callback_param *p = (callback_param *)param;
struct pollfd c_poll;
c_poll.fd = sockfd;
c_poll.events = POLLIN;
memset(buf, 0, sizeof(buf));
while (1) {
if (connect_state == STATE_CONNECTED) {
ret = poll(&c_poll, 1, 5000);
if (ret < 0) {
syslog(LOG_ERR, "poll error!\n");
break;
}
else if (0 == ret) {
if (send(sockfd, heartbeat_buf, sizeof(heartbeat_buf), 0) < 0) {
connect_state = STATE_DISCONNECTE;
syslog(LOG_ERR, "disconnect!\n");
break;
}
}
else {
if (recv(sockfd, buf, sizeof(buf), 0) > 0) {
syslog(LOG_INFO, "recv:%s\n", buf);
p->callback(buf, sizeof(buf));
}
}
}
else
break;
}
}
void tcp_register_callback(recv_callback cb)
{
pthread_t recv_t;
static callback_param param;
param.callback = cb;
pthread_create(&recv_t, NULL, thread_recv, (void *)param);
pthread_detach(recv_t);
}
main.c：
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include "hy_tcp.h"
#include "hy_udp.h"
#define PORT 6000 //服务器端口号
#if 1
void r_callback(char *msg, int len) {
}
int main(int argc, char *argv[])
{
char recv_buf = {0};
char send_buf = {0};
char str;
recv_callback func = r_callback;
if(argc < 2){
printf("required parameter missing\n");
return -1;
}
//tcp_dns_change(argv, str, sizeof(str));
tcp_connect(argv,PORT);
tcp_register_callback(func);
while(1){
memset(send_buf,0,sizeof(send_buf));
printf("please input something\n");
scanf("%s",send_buf);
tcp_send(send_buf);
}
tcp_disconnect();
return 0;
}
#endif
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