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Linux 套接字编程 - select

2024-07-18 00:50:27   224人阅读

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 256void 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


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