/* File: server.c */	#include <stdio.h>	#include <sys/types.h>	#include <sys/socket.h>	#include <netinet/in.h>	#include <sys/time.h>	int main(int argc, char **argv)	{		int fd;		int address_len;		struct sockaddr_in address;		fd_set fdset;		//建立套接口		fd = socket(AF_INET, SOCK_STREAM, 0);		//綁定地址和端口		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);		//建立套接口隊列		listen(fd, 64);				printf("waiting...");		while(1) {			struct sockaddr_in client_address;			int len;			int client_sockfd;			char *data = "Server to Client String!\n";			char data2[100];			struct timeval timeout;			//設置超時為 2 秒			timeout.tv_sec = 1;			timeout.tv_usec = 0;			//設置fdset			FD_ZERO(&fdset);			FD_CLR(fd, &fdset);			FD_SET(fd, &fdset);			if((select(fd+1, &fdset, NULL, NULL, &timeout))< 0){				printf("cannot select.\n");				fflush(stdout);			}			if(FD_ISSET(fd, &fdset)){				//有聯接到來				len = sizeof(client_address);				client_sockfd = accept(fd, 				(struct sockaddr *)&client_address, &len);				//接收數據				bzero((void *)data2, 100);				readline(client_sockfd, (void *)data2, 100);				printf("server read line:%s", data2);				//發送數據				writen(client_sockfd,(void *)data,strlen(data));				printf("server send line:%s", data);				close(client_sockfd);				printf("waiting...");				fflush(stdout);			} else {				printf(".");				fflush(stdout);			}		}	}