超时功能 [英] Timeout Function

问题描述

我想打一个code，其中用户的名称将被要求输入，但在15秒的时间限制。如果用户跨越极限和放大器;没有输入一个名称（或任何字符串），那么code将被终止和放大器; 超时按摩会显示姓名，否则应保存和放大器; 谢谢你按摩会显示。我曾尝试这样的，但它是错误的＆安培;不工作。请给我这个..感谢的解决方案。

 的#include＆LT;＆stdio.h中GT;
＃包括LT＆;＆time.h中GT;INT超时（INT秒）
{
    clock_t表示endwait;
    endwait =时钟（）+秒* CLOCKS_PER_SEC;
    而（时钟（）＆下; endwait）{}    返回1;
}诠释的main（）
{
    焦炭名[20];
    的printf（请输入用户名：（15秒），\\ n）;
    的printf（时间从现在做起！\\ n）;    scanf函数（％S，名）;
    如果（超时（5）== 1）{
        的printf（超时\\ n）;
        返回0;
    }    的printf（Thnaks \\ ​​n）;
    返回0;
}
 

解决方案

也许这虚拟程序可能会帮助您：

 的#include＆LT;＆stdio.h中GT;
＃包括LT＆;＆unistd.h中GT;
＃包括LT＆; SYS / time.h中＆GT;
＃包括LT＆; SYS / types.h中＆GT;＃定义等待3诠释的main（）
{
    焦炭名[20] = {0}; //在单个字符输入的情况下
    FD_SET input_set;
    timeval结构超时;
    INT ready_for_reading = 0;
    INT read_bytes = 0;    / *清空FD集* /
    FD_ZERO（安培; input_set）;
    / *听输入描述符* /
    FD_SET（0，＆放大器; input_set）;    / *等待几秒钟* /
    timeout.tv_sec =等待; //等待秒
    timeout.tv_usec = 0; // 0毫秒    / *邀请用户写的东西* /
    的printf（请输入用户名：（单位：％d秒）\\ n，等待）;
    的printf（时间从现在做起！\\ n）;    / *监听输入流的任何活动* /
    ready_for_reading =选择（1，＆安培; input_set，NULL，NULL，＆安培;超时）;
    / *在这里，第一个参数是文件描述符的数量设置，
     *第二个是我们的FD集阅读，
     *第三个是在任何写操作需要更新FD集，
     *这是不是在这种情况下，必需的。
     *四是超时
     * /    如果（ready_for_reading == -1）{
        / *一些错误发生在输入* /
        的printf（无法读取您的输入\\ n）;
        返回-1;
    }    如果（ready_for_reading）{
        read_bytes =读（0，名称，19）;
        如果（名称[read_bytes-1] =='\\ n'）{
        --read_bytes;
        名称[read_bytes] ='\\ 0';
        }
        如果（read_bytes == 0）{
            的printf（你只需点击进入\\ n）;
        }其他{
            的printf（读，从输入％d字节：％S \\ n，read_bytes，名）;
        }
    }其他{
        的printf（％d秒结束了 - 没有数据输入\\ n，等待）;
    }    返回0;
}
 

更新：结果
这是目前测试code。

另外，我采取了从人的提示为选择。本手册已包含正在被用于从在5秒内终端和超时在没有活动的情况下，读了code片段。

以防万一简要说明了code写得不好不够的：

1. 我们添加的输入流（ FD = 1 ）的FD集。


2. 我们启动选择打电话听为创建此FD集
   任何活动。


3. 在任何情况下的活动超时内发生期，即
   通过读通话读取。


4. 在情况下，有没有活动，超时发生。

希望这有助于。

I want to make a code in which Name of User will be asked to input, but in a time limit of 15 seconds. If user cross the limit & failed to input a name(or any string), then code will be terminated & "Time Out" Massage will be display otherwise Name should be saved & "Thanks" massage will be display. I had try like this but it's wrong & not working. Please give me a solution for this.. Thanks.

#include <stdio.h>
#include <time.h>

int timeout ( int seconds )
{
    clock_t endwait;
    endwait = clock () + seconds * CLOCKS_PER_SEC ;
    while (clock() < endwait) {}

    return  1;
}

int main ()
{
    char name[20];
    printf("Enter Username: (in 15 seconds)\n");
    printf("Time start now!!!\n");

    scanf("%s",name);
    if( timeout(5) == 1 ){
        printf("Time Out\n");
        return 0;
    }

    printf("Thnaks\n");
    return 0;
}

解决方案

Probably this dummy program might help you:

#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>

#define WAIT 3

int main ()
{
    char            name[20] = {0}; // in case of single character input
    fd_set          input_set;
    struct timeval  timeout;
    int             ready_for_reading = 0;
    int             read_bytes = 0;

    /* Empty the FD Set */
    FD_ZERO(&input_set );
    /* Listen to the input descriptor */
    FD_SET(0, &input_set);

    /* Waiting for some seconds */
    timeout.tv_sec = WAIT;    // WAIT seconds
    timeout.tv_usec = 0;    // 0 milliseconds

    /* Invitation for the user to write something */
    printf("Enter Username: (in %d seconds)\n", WAIT);
    printf("Time start now!!!\n");

    /* Listening for input stream for any activity */
    ready_for_reading = select(1, &input_set, NULL, NULL, &timeout);
    /* Here, first parameter is number of FDs in the set, 
     * second is our FD set for reading,
     * third is the FD set in which any write activity needs to updated,
     * which is not required in this case. 
     * Fourth is timeout
     */

    if (ready_for_reading == -1) {
        /* Some error has occured in input */
        printf("Unable to read your input\n");
        return -1;
    } 

    if (ready_for_reading) {
        read_bytes = read(0, name, 19);
        if(name[read_bytes-1]=='\n'){
        --read_bytes;
        name[read_bytes]='\0';
        }
        if(read_bytes==0){
            printf("You just hit enter\n");
        } else {
            printf("Read, %d bytes from input : %s \n", read_bytes, name);
        }
    } else {
        printf(" %d Seconds are over - no data input \n", WAIT);
    }

    return 0;
}

Update:
This is now tested code.

Also, I have taken hints from man for select. This manual already contains a code snippet which is being used to read from the terminal and timeout in 5 seconds in case of no activity.

Just a brief explanation in case the code is not well written enough:

1. We add the input stream (fd = 1) to the FD set.
2. We initiate select call to listen to this FD set created for any activity.
3. In case any activity occurs within the timeout period, that is read through the read call.
4. In case there was no activity, timeout occurs.

Hope this helps.

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