linux网络编程：select 的的问题
下面是 echo 服务器和客户端的程序，其中服务器端使用了 select 来监听套接字是否可读，在客户端只是使用简单的阻塞I/O，但是发现一个诡异的执行结果。

//服务器
#include "../unpv13e/lib/unp.h"

int main(int argc, char** argv)
{
int i,maxi,maxfd,listenfd,connfd,sockfd;
int nready,client[FD_SETSIZE];
ssize_t n;
fd_set rset,allset;
char buf[MAXLINE];
socklen_t clilen;
struct sockaddr_in cliaddr,servaddr;

listenfd = Socket(AF_INET,SOCK_STREAM,0);

bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(8080);

Bind(listenfd,(SA *) &servaddr,sizeof(servaddr));

Listen(listenfd,LISTENQ);

maxfd = listenfd;
maxi = -1;

for(i=0; i<FD_SETSIZE; i++)
client[i] = -1;

FD_ZERO(&allset);
FD_SET(listenfd,&allset);

for( ; ; ) 
{
rset = allset;
nready = Select(maxfd+1,&rset,NULL,NULL,NULL);//select listenfd

//printf("ready to read:%d\n",nready);
if(FD_ISSET(listenfd,&rset))
{
clilen = sizeof(cliaddr);
connfd = Accept(listenfd,(SA *)&cliaddr,&clilen);

for(i=0; i<FD_SETSIZE; i++)//put connfd into client array
{
if(client[i] < 0)
{
client[i] = connfd;
break;
}//if
}//for

if(i == FD_SETSIZE)
err_quit("too many clients");

FD_SET(connfd,&allset);

if(connfd > maxfd)
maxfd = connfd;

if(i > maxi)
i = maxi;

if(--nready <= 0)//maybe there is only listenfd that is ready to read
continue;
}//if

printf("reading:%d\n",maxi);
for(i=0; i<=maxi; i++)
{
if( (sockfd = client[i]) < 0)
continue;

if(FD_SET(sockfd,&rset))
{
if( (n=Read(sockfd,buf,MAXLINE)) == 0)//FIN
{
Close(sockfd);
FD_CLR(sockfd,&allset);
client[i] = -1;
}
else if(n < 0)//socket error
err_quit("socket error");
else
Writen(sockfd,buf,n);

if(--nready <= 0)break;
}//if
}//for
}//for

return 0;
}

//客户端
#include "../unpv13e/lib/unp.h"

void str_cli(FILE *fp,int sockfd)
{
char sendline[MAXLINE],recvline[MAXLINE];

while(Fgets(sendline,MAXLINE,fp) != NULL)
{
Writen(sockfd,sendline,strlen(sendline));

if(Readline(sockfd,recvline,MAXLINE) == 0)
err_quit("str_cli:server terminated prematurely");

Fputs(recvline,stdout);
}//while
}

int main(int argc,char **argv)
{
int sockfd;
struct sockaddr_in servaddr;

if(argc != 2)
err_quit("usage:tcpcli <IPaddress>");

sockfd = Socket(AF_INET,SOCK_STREAM,0);

bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(8080);
Inet_pton(AF_INET,argv[1],&servaddr.sin_addr); 
 

Connect(sockfd,(SA *)&servaddr,sizeof(servaddr));

str_cli(stdin,sockfd);

exit(0);
}

测试的时候，先启动服务器，接着启动客户端，然后在客户端输入字符串，但是服务器的输出结果：
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
reading:-1
........

而且在强制结束客户端的时候，依然没有阻止以上输出！ Linux 网络编程 select 服务器
[解决办法]
你自己赋值的maxi = -1;你问谁呢。