Linux 套接字编程 - select

select 可以感知文件表述符集合中的变化，如果办fd0（即标准输入）放入select的read fd set，发现只有按回车的时候select才会返回。查了下要把终端的缓冲大小设为1，这样就能实现击键后马上反应了。

#include <stdio.h>

#include <stdlib.h>



#include <unistd.h>

#include <errno.h>

#include <termio.h>



#include <sys/time.h>

#include <sys/types.h>



#define BUF_SIZE 256



void setup_terminal(struct termios* old_args);



void reset_terminal(struct termios* old_args);



int main() {

        struct termios old_args;



        setup_terminal(&old_args);



        fd_set rfds;

        int sres = 0;



        char buffer[BUF_SIZE];

        int nread = 0;



        for (;;) {

                /* reset read file descriptor set */

                FD_ZERO(&rfds);

                /* add standard input file descriptor to the set */

                FD_SET(0, &rfds);



                /* do blocking select */

                printf("\nselect begin\n");

                sres = select(0 + 1, &rfds, NULL, NULL, NULL);

                printf("\nselect return\n");



                if (sres < 0) {

                        perror("select error");

                        break;

                } else if (sres == 0) {

                        /* should not be here for blocked select without timeout*/

                        printf("select timeout\n");

                } else {

                        if (FD_ISSET(0, &rfds)) {

                                nread = read(0, buffer, sizeof(buffer)-1);

                                if (nread <= 0) {

                                        perror("read error");

                                        break;

                                }

                                buffer[nread] = '\0';

                                printf("read string(%d): %s\n", nread, buffer);

                        }

                }



        }

        reset_terminal(&old_args);

        return 0;

}



void setup_terminal(struct termios* old_args) {

        tcgetattr(0, old_args);



        struct termios new_args = *old_args;

        new_args.c_lflag &= ~ICANON;

        new_args.c_cc[VMIN] = 1;



        tcsetattr(0, TCSANOW, &new_args);

}



void reset_terminal(struct termios* old_args) {

        tcsetattr(0, TCSANOW, old_args);

}

记得很早之前也一致想实现这个功能，终于如愿，虽然和socket编程没什么太大关系。

参考：

http://tieba.baidu.com/p/685575698