select例程

#include <sys/types.h> 
#include <sys/time.h> 
#include <stdio.h> 
#include <fcntl.h> 
#include <sys/ioctl.h> 
#include <unistd.h> 

int main() 
{ 
    char buffer[128]; 
    int result, nread; 
    fd_set inputs, testfds; 
    struct timeval timeout; 
    FD_ZERO(&inputs);//用select函数之前先把集合清零  
     FD_SET(0,&inputs);//把要检测的句柄——标准输入（0），加入到集合里。
     while(1) 
    { 
       testfds = inputs; 
       timeout.tv_sec = 2; 
       timeout.tv_usec = 500000; 
       result = select(FD_SETSIZE, &testfds, (fd_set *)0, (fd_set *)0, &timeout); 
       switch(result) 
       { 
       case 0: 
           printf("timeout/n"); 
	       break;
	   case -1: 
           perror("select"); 
           exit(1); 
       default: 
           if(FD_ISSET(0,&testfds)) 
           { 
               ioctl(0,FIONREAD,&nread);//取得从键盘输入字符的个数，包括回车。 
               if(nread == 0) 
               { 
                  printf("keyboard done/n"); 
                  exit(0); 
               } 
               nread = read(0,buffer,nread); 
               buffer[nread] = 0; 
               printf("read %d from keyboard: %s", nread, buffer); 
         } 
         break; 
      } 
   } 
   return 0;
} 

#include <sys/types.h> 
#include <sys/socket.h> 
#include <stdio.h> 
#include <netinet/in.h> 
#include <sys/time.h> 
#include <sys/ioctl.h> 
#include <unistd.h> 

int main() 
{ 
	int server_sockfd, client_sockfd; 
	int server_len, client_len; 
	struct sockaddr_in server_address; 
	struct sockaddr_in client_address; 
	int result; 
	fd_set readfds, testfds; 
	server_sockfd = socket(AF_INET, SOCK_STREAM, 0);//建立服务器端socket 
	server_address.sin_family = AF_INET; 
	server_address.sin_addr.s_addr = htonl(INADDR_ANY); 
	server_address.sin_port = htons(9734); 
	server_len = sizeof(server_address); 
	bind(server_sockfd, (struct sockaddr *)&server_address, server_len); 
	listen(server_sockfd, 5); 
	FD_ZERO(&readfds); 
	FD_SET(server_sockfd, &readfds);//将服务器端socket加入到集合中
	while(1) 
	{
		char ch;                
		int fd; 
		int nread; 
		testfds = readfds; 
		printf("server waiting/n"); 

		/*无限期阻塞，并测试文件描述符变动 */
		result = select(FD_SETSIZE, &testfds, (fd_set *)0,(fd_set *)0, (struct timeval *) 0); 
		if(result < 1) 
		{ 
			perror("server5"); 
			exit(1); 
		} 

		/*扫描所有的文件描述符*/
		for(fd = 0; fd < FD_SETSIZE; fd++) 
		{
			/*找到相关文件描述符*/
			if(FD_ISSET(fd,&testfds)) 
			{ 
		     	        /*判断是否为服务器套接字，是则表示为客户请求连接。*/
				if(fd == server_sockfd) 
				{ 
					client_len = sizeof(client_address); 
					client_sockfd = accept(server_sockfd, 
					(struct sockaddr *)&client_address, &client_len); 
					FD_SET(client_sockfd, &readfds);//将客户端socket加入到集合中
					printf("adding client on fd %d/n", client_sockfd); 
				} 

				/*客户端socket中有数据请求时*/
				else 
				{                                          
					ioctl(fd, FIONREAD, &nread);//取得数据量交给nread
					
					/*客户数据请求完毕，关闭套接字，从集合中清除相应描述符 */
					if(nread == 0) 
					{ 
						close(fd); 
						FD_CLR(fd, &readfds); 
						printf("removing client on fd %d/n", fd); 
					} 

					/*处理客户数据请求*/
					else 
					{ 
						read(fd, &ch, 1); 
						sleep(5); 
						printf("serving client on fd %d/n", fd); 
						ch++; 
						write(fd, &ch, 1); 
					} 
				} 
			} 
		} 
	} 
} 

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

int main() 
{ 
    int client_sockfd; 
    int len; 
    struct sockaddr_in address;//服务器端网络地址结构体                                           
     int result; 
    char ch = 'A'; 
    client_sockfd = socket(AF_INET, SOCK_STREAM, 0);//建立客户端socket                               
    address.sin_family = AF_INET; 
    address.sin_addr.s_addr = inet_addr(“127.0.0.1”);             
    address.sin_port = 9734; 
    len = sizeof(address); 
    result = connect(client_sockfd, (struct sockaddr *)&address, len); 
    if(result == -1) 
    { 
         perror("oops: client2"); 
         exit(1); 
    } 
    write(client_sockfd, &ch, 1); 
    read(client_sockfd, &ch, 1); 
    printf("char from server = %c/n", ch); 
    close(client_sockfd); 
    zexit(0); 
}