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

//*********************************announce*****************




//********************************params*******************





 
int main(int argc, char* argv[])
{
    struct timeval timeout={0,0};
    int server_sockfd,maxfdp;
    struct sockaddr_in server_addr, client_addr;
    char recv_buf[100];
    int nbytes = 0;
    socklen_t len = 0;
    fd_set fds;
    // create socket 
    server_sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (server_sockfd < 0)
    {
    printf("error create\n");
    return -1;
    }
    printf("create success\n");

    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//get any ip
    server_addr.sin_port = htons(atoi(argv[1]));//set port 
    bind(server_sockfd, (struct sockaddr *) &server_addr, sizeof(server_addr));
    printf("bind success\n");
    len = sizeof(client_addr);
    while(1) 
    { 
        printf("check\n");
        FD_ZERO(&fds); //每次循环都要清空集合，否则不能检测描述符变化
        FD_SET(server_sockfd,&fds); //添加描述符 
        
        maxfdp=server_sockfd+1;    //描述符最大值加1
        int res=select(maxfdp,&fds,&fds,NULL,&timeout);
        printf("%d\n",res);
        switch(res)   //select使用 
        { 
            case -1: exit(-1);break; //select错误，退出程序 
            case 0:
                printf("timeout\n");
                break; //再次轮询
            default: 
            if(FD_ISSET(0,&fds)){
                fgets(recv_buf, 100, stdin);
                sendto(server_sockfd,recv_buf,strlen(recv_buf),0,(struct sockaddr *)&client_addr,len);
            }
            if(FD_ISSET(server_sockfd,&fds)){ 
                nbytes=recvfrom(server_sockfd, recv_buf, 100, 0, (struct sockaddr *)&client_addr, &len);//接受网络数据 
                printf("recv %d bytes:%s.\n", nbytes, recv_buf);
            }// end if break; 
        }// end switch 
    }//end while 


 
    return 0;
}

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
 
int main(int argc, char* argv[])
{
  int sock_fd;
  struct sockaddr_in server_addr;
  char recv_buf[100];
  int nbytes = 0;
  socklen_t len = 0;
 
  /* 创建Socket */
  sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
  if (sock_fd < 0)
  {
    printf("客户端Socket创建失败");
    return -1;
  }
 
  /* 绑定ip和端口 */
  bzero(&server_addr, sizeof(server_addr));
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = inet_addr(argv[1]);
  server_addr.sin_port = htons(atoi(argv[2]));//指定端口号
  while(1)
  {
      len = sizeof(server_addr);
    //接收用户输入，发送给服务端
    printf("请输入要发送给服务端的数据:");
      fgets(recv_buf, 100, stdin);
    sendto(sock_fd,recv_buf,100,0,(struct sockaddr *)(&server_addr),len);
     
    /* 接收UDP客户端的数据 */
    /*
    len = sizeof(server_addr);
    nbytes = recvfrom(sock_fd, recv_buf, 100, 0, (struct sockaddr *)&server_addr, &len);
    recv_buf[nbytes] = '\0';
    printf("recv %d bytes:%s.\n", nbytes, recv_buf);
   */
  }
 
  return 0;
}