Linux网络编程：I/O复用之select详解(2)

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>

//接收线程：负责接收消息并显示
void *recv_thread(void* arg)
{
 int udpfd = (int)arg;
 struct sockaddr_in addr;
 socklen_t addrlen = sizeof(addr);
 
 bzero(&addr,sizeof(addr));
 while(1)
 {
  char buf[200]  = "";
  char ipbuf[16] = "";
  recvfrom(udpfd, buf, sizeof(buf), 0, (struct sockaddr*)&addr, &addrlen);
  printf("\r\033[31m[%s]:\033[32m%s\n",inet_ntop(AF_INET,&addr.sin_addr,ipbuf,sizeof(ipbuf)),buf);
  write(1,"UdpQQ:",6);
 }
 return NULL;
}

int main(int argc,char *argv[])
{
 char buf[100] = "";
 int  udpfd = 0;
 pthread_t tid;
 struct sockaddr_in addr;
 struct sockaddr_in cliaddr;
 
 //对套接字地址进行初始化
 bzero(&addr,sizeof(addr));
 addr.sin_family = AF_INET;
 addr.sin_port  = htons(8000);
 addr.sin_addr.s_addr = htonl(INADDR_ANY);

bzero(&cliaddr,sizeof(cliaddr)); 
 cliaddr.sin_family = AF_INET;
 cliaddr.sin_port  = htons(8000);

//创建套接口
 if( (udpfd = socket(AF_INET,SOCK_DGRAM, 0)) < 0)
 {
  perror("socket error");
  exit(-1);
 }
 
 //设置端口
 if(bind(udpfd, (struct sockaddr*)&addr, sizeof(addr)) < 0)
 {
  perror("bind error");
  close(udpfd); 
  exit(-1);
 }
 
 printf("input: \"sayto 192.168.221.X\" to sendmsg to somebody\n");
 //创建接收线程
 pthread_create(&tid, NULL, recv_thread, (void*)udpfd); //创建线程
 printf("\033[32m"); //设置字体颜色
 fflush(stdout);
 
 while(1)
 { 
  //主线程负责发送消息
  write(1,"UdpQQ:",6);//1 表示标准输出
  fgets(buf, sizeof(buf), stdin); //等待输入
  buf[strlen(buf) - 1] = '\0';    //确保输入的最后一位是'\0'
  if(strncmp(buf, "sayto", 5) == 0)
  {
   char ipbuf[INET_ADDRSTRLEN] = "";
   inet_pton(AF_INET, buf+6, &cliaddr.sin_addr);//给addr套接字地址再赋值.
   printf("\rconnect %s successful!\n",inet_ntop(AF_INET,&cliaddr.sin_addr,ipbuf,sizeof(ipbuf)));
   continue;
  }
  else if(strncmp(buf, "exit",4) == 0)
  {
   close(udpfd);
   exit(0);
  }
 
  sendto(udpfd, buf, strlen(buf),0,(struct sockaddr*)&cliaddr, sizeof(cliaddr));
 }
 
 return 0;
}

运行结果：

用select来完成上述同样的功能：

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int argc,char *argv[])
{
 int udpfd = 0;
 struct sockaddr_in saddr;
 struct sockaddr_in caddr;

bzero(&saddr,sizeof(saddr));
 saddr.sin_family = AF_INET;
 saddr.sin_port  = htons(8000);
 saddr.sin_addr.s_addr = htonl(INADDR_ANY);
 
 bzero(&caddr,sizeof(caddr));
 caddr.sin_family  = AF_INET;
 caddr.sin_port    = htons(8000);
 
 //创建套接字
 if( (udpfd = socket(AF_INET,SOCK_DGRAM, 0)) < 0)
 {
  perror("socket error");
  exit(-1);
 }
 
 //套接字端口绑字
 if(bind(udpfd, (struct sockaddr*)&saddr, sizeof(saddr)) != 0)
 {
  perror("bind error");
  close(udpfd); 
  exit(-1);
 }