CODEWITHSUNDEEP
clinux
laura
laura

Reputation: 2135

Linux issues on setting a timer function

I am creating a process with 2 children, 1 of the children is responsible to read questions (line by line from a file), output every question and reading the answer, and the other one is responsable to measure the time elapsed and notify the user at each past 1 minute about the remaining time. My problem is that i couldn't find any useful example of how i can make this set time function to work. Here is what i have tried so far. The problem is that it outputs the same elapsed time every time and never gets out from the loop.

#include<time.h>
#define T 600000

int main(){
  clock_t start, end;
  double elapsed;
  start = clock();
  end = start + T;
  while(clock() < end){
     elapsed = (double) (end - clock()) / CLOCKS_PER_SEC;
     printf("you have %f seconds left\n", elapsed);
     sleep(60);
  }
  return 0;
}

Upvotes: 1

Views: 306

Answers (2)

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

As I commented, you should read the time(7) man page.

Notice that clock(3) measure processor time, not real time. I suggest using clock_gettime(2) with CLOCK_REALTIME (or perhaps CLOCK_MONOTONIC). See also localtime(3) and strftime(3). Also timer_create(2), the Linux specific timerfd_create(2) and poll(2) etc... Read also Advanced Linux Programming.

If you dare use signals, read carefully signal(7). But timerfd_create and poll should probably be enough to you.

Upvotes: 2

Jonathan Ben-Avraham
Jonathan Ben-Avraham

Reputation: 4821

Here is something simple that seems to work:

#include <stdio.h>
#define TIME    300

int main()
{
    int i;

    for (i=TIME; i > 0; i--)
    {
            printf("You have [%d] minutes left.\n", i/60);
            sleep(60);
    }
}

Give it a try.

Upvotes: 0

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