UDP是无连接的，不可靠的数据协议报，而TCP是面向连接的，提供可靠的字节流。然而在有些情况下更适合用UDP而不是TCP。有些流行的应用程序是用UDP实现的：DNS（域名系统），NFS（网络文件系统）和SNMP（简单网络管理协议）等
1 #include<unistd.h> 2 #include<sys/types.h> 3 #include<sys/socket.h> 4 #include<arpa/inet.h> 5 #include<stdio.h> 6 #include<errno.h> 7 #include<stdlib.h> 8 int main() 9 { 10 int sockfd=socket(AF_INET,SOCK_DGRAM,0); 11 12 struct sockaddr_in saddr; 13 saddr.sin_family=AF_INET; 14 saddr.sin_port=htons(7319); 15 inet_pton(AF_INET,"192.168.6.11",&saddr.sin_addr.s_addr); 16 17 int ret=bind(sockfd,(struct sockaddr *)&saddr,sizeof(saddr)); 18 if(ret<0) 19 { 20 perror("bind failed:"); 21 exit(0); 22 } 23 24 char buf[20]; 25 char addr[20]; 26 struct sockaddr_in caddr; 27 int len=sizeof(caddr); 28 while(1) 29 { 30 ret=recvfrom(sockfd,buf,20,0,(struct sockaddr *)&caddr,&len); 31 if(ret<=0) 32 { 33 printf("recvfrom error:\n"); 34 close(sockfd); 35 exit(0); 36 } 37 puts(buf); 38 printf("port:%d addr:%s\n",ntohs(caddr.sin_port),inet_ntop(AF_INET,& 39 caddr.sin_addr.s_addr,addr,20)); 40 } 41 close(sockfd); 42 return 0; 43 }
1 #include<unistd.h> 2 #include<stdlib.h> 3 #include<sys/types.h> 4 #include<sys/socket.h> 5 #include<arpa/inet.h> 6 #include<stdio.h> 7 #include<errno.h> 8 #include<string.h> 9 int main() 10 { 11 int sockfd=socket(AF_INET,SOCK_DGRAM,0); 12 struct sockaddr_in saddr; 13 saddr.sin_family=AF_INET; 14 saddr.sin_port=htons(7319); 15 inet_pton(AF_INET,"192.168.6.11",&saddr.sin_addr.s_addr); 16 17 char buf[20]; 18 int ret; 19 while(1) 20 { 21 printf("请输入buf:"); 22 scanf("%s",buf); 23 ret=sendto(sockfd,buf,strlen(buf)+1,0,(struct sockaddr *)&saddr,size 24 of(saddr)); 25 printf("ret=%d\n",ret); 26 } 27 close(sockfd); 28 return 0; 29 }
效果如下：