select函数的用法一

这个例子来自网上，调试修改后，粘贴如下：

#include <sys/time.h>#include <sys/types.h>#include <sys/stat.h>#include <assert.h>#include <unistd.h>#include <fcntl.h>int main(int argc, char **argv){int keyboard;int ret;char ch;fd_set readfd;struct timeval timeout;keyboard = open("/dev/tty", O_RDONLY|O_NONBLOCK);assert(keyboard > 0);while (1){timeout.tv_sec  = 3;timeout.tv_usec = 0;FD_ZERO(&readfd);FD_SET(keyboard, &readfd); // 置位// 执行select函数时，首先记录置位的描述符，然后将所有位清零，从select函数返回前，有动作的描述符被再次置位ret = select(keyboard+1, &readfd, NULL, NULL, &timeout);if (FD_ISSET(keyboard, &readfd)) { // 如果置位，则表示有可读的信息read(keyboard, &ch, 1);if ('\n' == ch)continue;printf("key:%c\n", ch);if ('q' == ch)break;}else {printf("No input!\n");}}close(keyboard);}

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