udp -socket编程

//==================================UDPClient.c=================================== #include <sys/types.h> #include <sys/socket.h> #include <string.h> #include <netinet/in.h> #include <stdio.h> #include <stdlib.h> #include <error.h> #define SERV_PORT 15811 #define MAXLINE 100 int main(int argc, char **argv) { int sockfd,so_broadcast; struct sockaddr_in servaddr; if( argc!=2 ) perror("usage:udpclient<IPaddress>"); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(SERV_PORT); char sendline[MAXLINE]; char recvline[MAXLINE]; sockfd = socket(AF_INET, SOCK_DGRAM, 0); //設置广播属性 if (setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &so_broadcast, sizeof(so_broadcast))) { perror("setsockopt"); return ; } if (sockfd == -1) { perror("socket"); return ; } while(fgets(sendline, MAXLINE,stdin)!=NULL) { //指定发送的IP（可以如192.168.18.255－－多播），以下两方法皆可 inet_pton(AF_INET,argv[1],&servaddr.sin_addr); //servaddr.sin_addr.s_addr = inet_addr(argv[1]); sendto(sockfd,sendline,strlen(sendline),0,(struct sockaddr *)&servaddr,sizeof(servaddr)); memset(recvline,0,sizeof(recvline)); int n=recvfrom(sockfd,recvline,MAXLINE,0,NULL,NULL); if(n>0) { fputs(recvline,stdout); } } exit(0); }