我想找到一种方法退出“有问题的循环”（见下文）并保持程序运行，我的意思是：在程序中必须有消息：“准备发送信息，退出停止！” 如果用户不键入 exit，程序必须仍在运行，而无需等待用户单击字符然后输入。信息必须连续发送，直到用户键入 exit 退出程序。
我希望我能很好地解释这个问题，并且我确信有一个简单的解决方案
预先感谢您的帮助
do
{
/* menu */
printf("\r\n");
printf("1 : Start, Sending Informations.\r\n");
printf("2 : Quit.\r\n");
printf("choice : ");
scanf("%d", &nChoice);
printf("\n Trying to do a connection \n \r");
/* if connection is not established, call accept, TCP SERVER */
if (fd_client == -1)
{
printf("ready to accept...\n");
fd_client = accept(fd_listen, (struct sockaddr*)&client_addr, &addrlen);
if (fd_client >= 0)
{
printf("accept: %s, port %d\r\n", inet_ntoa(client_addr.sin_addr), htons(client_addr.sin_port));
}
}
if (fd_client < 0)
{
printf(" connection is not established, continue to accept\n");
/*connection is not established, continue to accept*/
continue;
}
FD_ZERO(&rfd);
FD_ZERO(&wfd);
FD_ZERO(&efd);
FD_SET(fd_tty, &rfd);
FD_SET(fd_client, &rfd);
maxfd = (fd_tty > fd_client ? fd_tty : fd_client) + 1;
/*connection is established, call select to see if any data arrived from the GPS*/
printf("connection is established, seeing if any data arrived\n");
char chaine1[256];
char chaine2[] = "exit";
int i;
if (nChoice == 1)
{
do // THE LOOP IN QUESTION
{
printf("preparing to send informations, exit to stop !\n");
i = strcmp(chaine1, chaine2); // Building the condition to exit
scanf("%s", chaine1);
fflush(stdin);
// printf ("i= %d\n",i);
ret = select(maxfd, &rfd, &wfd, &efd, &tm);
if (ret < 0) // Select failed
{
printf("select fail\r\n");
break;
}
else if (ret == 0)
{
continue; /*no data arrived, continue to call select*/
}
else
printf("data is arriving \n");
if (FD_ISSET(fd_tty, &rfd)) /*tty port has data to be read*/
{
ret = read(fd_tty, buf, sizeof(buf));
if (ret <= 0)
{
printf("read tty port fail\r\n");
break;
}
if (send(fd_client, buf, ret, 0) < 0) /*send data to ethernet*/
{
printf("send to ethernet fail\r\n");
break;
}
}
if (FD_ISSET(fd_client, &rfd)) /*tcp client has data to be read*/
{
ret = recv(fd_client, buf, sizeof(buf), 0);
if (ret < 0)
{
printf("read from ethernet fail\r\n");
break;
}
else if (ret == 0)
{
printf("disconnect by remote\r\n");
close(fd_client);
fd_client = -1;
continue; /*continue to accept...*/
}
if (write(fd_tty, buf, ret) < 0) /*send data to tty port*/
{
printf("write to tty fail\r\n");
break;
}
}
} while (i != 0 ); // The exit condition
}
} while(nChoice != 2);