/* File: server.c */	#include <stdio.h>	#include <sys/types.h>	#include <sys/socket.h>	#include <netinet/in.h>	int main(int argc, char **argv)	{		int fd;		int address_len;		struct sockaddr_in address;		//建立套接口		fd = socket(AF_INET, SOCK_DGRAM, 0);	//SOCK_DGRAM		//綁定地址和端口		bzero(&address, sizeof(address));		address.sin_family = AF_INET;		address.sin_addr.s_addr = htonl(INADDR_ANY);		address.sin_port = htons(1234);		address_len = sizeof(address);		bind(fd, (struct sockaddr *)&address, address_len);		while(1) {			struct sockaddr_in client_address;			socklen_t len = sizeof(client_address);			int n;			char line[80];			printf("waiting...");			fflush(stdout);			//接收數(shù)據(jù)			n = recvfrom(fd, line, 80, 0, 				(struct sockaddr *)&client_address, &len);			printf("server received %d:%s", n, line);			//發(fā)送數(shù)據(jù)			sendto(fd, line, n, 0, 				(struct sockaddr *)&client_address, len);		}	}