《后台开发：核心技术与应用实践》第七章网络IO模型

#include <sys/time.h>  
#include <stdio.h>  
#include <sys/types.h>  
#include <sys/stat.h>  
#include <fcntl.h>  
#include <assert.h>  
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/select.h>
int main(){
	int keyboard;  
	int ret,i;  
	char c;  
	fd_set readfd;  
	struct timeval timeout;
	keyboard = open("/dev/tty",O_RDONLY | O_NONBLOCK); 
	assert(keyboard>0);  
	while(1){
		timeout.tv_sec=1; 
		timeout.tv_usec=0; 
		FD_ZERO(&readfd);  //将readfd清零
		FD_SET(keyboard,&readfd);//将keyboard加入readfd
		ret=select(keyboard+1,&readfd,NULL,NULL,&timeout); 
		if(FD_ISSET(keyboard,&readfd))//如果keyboard在readfd中，则为真 
		{
			i=read(keyboard,&c,1);  
			if('\n'==c)  
				continue;  
			printf("The input is %c\n",c);  
			if ('q'==c)  
				break;  
		}
	}
    return 0;
}

timeout.tv_sec=1; 
		timeout.tv_usec=0; 
		FD_ZERO(&readfd);  //将readfd清零
		FD_SET(keyboard,&readfd);//将keyboard加入readfd
		ret=select(keyboard+1,&readfd,NULL,NULL,&timeout);

if(FD_ISSET(keyboard,&readfd))//如果keyboard在readfd中，则为真 
		{
			i=read(keyboard,&c,1);  
			if('\n'==c)  
				continue;  
			printf("The input is %c\n",c);  
			if ('q'==c)  
				break;  
		}

#include <sys/time.h>  
#include <stdio.h>  
#include <sys/types.h>  
#include <sys/stat.h>  
#include <fcntl.h>  
#include <assert.h>  
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/select.h>
int main(){
	int keyboard; 
	int ret,i; 
	char c;
	fd_set readfd;
	struct timeval timeout;
	keyboard = open("/dev/tty",O_RDONLY | O_NONBLOCK);
	assert(keyboard>0);
	while(1) {
		timeout.tv_sec=5;
		timeout.tv_usec=0;
		FD_ZERO(&readfd);
		FD_SET(keyboard,&readfd);
		ret=select(keyboard+1,&readfd,NULL,NULL,&timeout);
		if (ret == -1)
			perror("select error");
		else if (ret){
			if(FD_ISSET(keyboard,&readfd)){
				i=read(keyboard,&c,1);
				if('\n'==c)
					continue;
				printf("hehethe input is %c\n",c);
				if ('q'==c)
					break;
			}  
               }else if (ret == 0)
                   printf("time out\n");
	}
	return 0;
}

if (ret == -1)
			perror("select error");
		else if (ret){
			if(FD_ISSET(keyboard,&readfd)){
				i=read(keyboard,&c,1);
				if('\n'==c)
					continue;
				printf("hehethe input is %c\n",c);
				if ('q'==c)
					break;
			}  
               }else if (ret == 0)
                   printf("time out\n");
	}

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/wait.h>
#include <string.h>
#include <errno.h>
#define DEFAULT_PORT 6666
int main( int argc, char ** argv){
    int serverfd,acceptfd; /* 监听socket: serverfd,数据传输socket: acceptfd */
    struct sockaddr_in my_addr; /* 本机地址信息 */
    struct sockaddr_in their_addr; /* 客户地址信息 */
    unsigned int sin_size, myport=6666, lisnum=10;
    if ((serverfd = socket(AF_INET , SOCK_STREAM, 0)) == -1) {
       perror("socket" );
       return -1;
    }
    printf("socket ok \n");
    my_addr.sin_family=AF_INET;
    my_addr.sin_port=htons(DEFAULT_PORT);
    my_addr.sin_addr.s_addr = INADDR_ANY;
    bzero(&(my_addr.sin_zero), 0);
    if (bind(serverfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr )) == -1) {
        perror("bind" );
        return -2;
    }
    printf("bind ok \n");
    if (listen(serverfd, lisnum) == -1) {
        perror("listen" );
        return -3;
    }
    printf("listen ok \n");
	
	fd_set client_fdset;	/*监控文件描述符集合*/
	int maxsock;            /*监控文件描述符中最大的文件号*/
	struct timeval tv;		/*超时返回时间*/
	int client_sockfd[5];   /*存放活动的sockfd*/
	bzero((void*)client_sockfd,sizeof(client_sockfd));
	int conn_amount = 0;    /*用来记录描述符数量*/
	maxsock = serverfd;
	char buffer[1024];
	int ret=0;
	while(1)
	{
		/*初始化文件描述符号到集合*/
		FD_ZERO(&client_fdset);
		/*加入服务器描述符*/
	FD_SET(serverfd,&client_fdset);//把服务器描述符加入到集合中
	/*设置超时时间*/
	tv.tv_sec = 30; /*30秒*/
	tv.tv_usec = 0;
	/*把活动的句柄加入到文件描述符中*/
	for(int i = 0; i < 5; ++i){
/*程序中Listen中参数设为5,故i必须小于5*/
	    if(client_sockfd[i] != 0){
	        FD_SET(client_sockfd[i], &client_fdset);
	    }
     }
	/*printf("put sockfd in fdset!\n");*/
	/*select函数*/
	ret = select(maxsock+1, &client_fdset, NULL, NULL, &tv);
	if(ret < 0){
	    perror("select error!\n");
	    break;
	}
	else if(ret == 0){
	    printf("timeout!\n");
	    continue;
	}
	/*轮询各个文件描述符*/
	for(int i = 0; i < conn_amount; ++i)
	{
	/*FD_ISSET检查client_sockfd是否可读写，>0可读写*/
	    if(FD_ISSET(client_sockfd[i], &client_fdset))
		{
	        printf("start recv from client[%d]:\n",i);
	        ret = recv(client_sockfd[i], buffer, 1024, 0);
	        if(ret <= 0)
			{
				printf("client[%d] close\n", i);
				close(client_sockfd[i]);
				FD_CLR(client_sockfd[i], &client_fdset);
				client_sockfd[i] = 0;
	        }
	        else
			{
				printf("recv from client[%d] :%s\n", i, buffer);
	        }
	    }
	}
	/*检查是否有新的连接，如果有，接收连接，加入到client_sockfd中*/
	if(FD_ISSET(serverfd, &client_fdset))
	{
		/*接受连接*/
		struct sockaddr_in client_addr;
		size_t size = sizeof(struct sockaddr_in);
		int sock_client = accept(serverfd, (struct sockaddr*)(&client_addr), (unsigned int*)(&size));
		if(sock_client < 0)
		{
			perror("accept error!\n");
			continue;
		}
	/*把连接加入到文件描述符集合中*/
	if(conn_amount < 5)
	{
		client_sockfd[conn_amount++] = sock_client;
		bzero(buffer,1024);
		strcpy(buffer, "this is server! welcome!\n");
		send(sock_client, buffer, 1024, 0);
		printf("new connection client[%d] %s:%d\n", conn_amount, inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
		bzero(buffer,sizeof(buffer));
		ret = recv(sock_client, buffer, 1024, 0);
		if(ret < 0)
		{
			perror("recv error!\n");
			close(serverfd);
			return -1;
		}
		printf("recv : %s\n",buffer);
		if(sock_client > maxsock)
		{
			maxsock = sock_client;
		}
		else
		{
			printf("max connections!!!quit!!\n");
			break;
		}
    }
    }
}

	for(int i = 0; i < 5; ++i)
	{
		if(client_sockfd[i] != 0){
			close(client_sockfd[i]);
		}
	}
	
	close(serverfd);
	return 0;	
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#define DEFAULT_PORT 6666
int main( int argc, char * argv[]){
    int connfd = 0;
    int cLen = 0;
    struct sockaddr_in client;
    if(argc < 2){
        printf(" Uasge: clientent [server IP address]\n");
        return -1;
    }	
    client.sin_family = AF_INET;
    client.sin_port = htons(DEFAULT_PORT);
    client.sin_addr.s_addr = inet_addr(argv[1]);
    connfd = socket(AF_INET, SOCK_STREAM, 0);
    if(connfd < 0){
	    perror("socket" );
        return -1;
    }
    if(connect(connfd, (struct sockaddr*)&client, sizeof(client)) < 0){
 	    perror("connect" );
        return -1;
    }
	char buffer[1024];
	bzero(buffer,sizeof(buffer));
	recv(connfd, buffer, 1024, 0);
	printf("recv : %s\n", buffer);
	bzero(buffer,sizeof(buffer));
	strcpy(buffer,"this is client!\n");
	send(connfd, buffer, 1024, 0);
	while(1){
		bzero(buffer,sizeof(buffer));
		scanf("%s",buffer);
		int p = strlen(buffer);
		buffer[p] = '\0';
		send(connfd, buffer, 1024, 0);
		printf("i have send buffer\n");
	}
	close(connfd);
	return 0;
}

all:server client
server:server.o
	g++ -g -o server server.o
client:client.o
	g++ -g -o client client.o
server.o:server.cpp
	g++ -g -c server.cpp
client.o:client.cpp
	g++ -g -c client.cpp
clean:all
	rm all