Thread: sleeping for some seconds

Hello!

I'm writing a program that have to write every 1.654 seconds (this number is random). The real time I have to wait is calculated and safe in a double type variable. Does anybody know how to make it? I've tried with nanosleep and usleep. But when I try to handle the time variables all goes crazy! Thank for your help.

I'll try to explain better. Sorry.

I want to make a program that every 0.5 secs makes a printf("It has passed 0.5 sec"). I don't mind if the precision isn't very good.

The problem with the time variables is that I don't know wich values gives to a variable that is of time_t for example.

I think of using a solution like these one:

Code:

int time_sec;
int time_usec;

time_sec = 0;
time_usec = 500000;

while(TRUE){

sleep(time_sec);
usleep(time_usec);
printf("It has passed %f sec\n",time_sec+time_usec*1e-6);

}

Originally Posted by matsp

Not sure what you mean you want to do with time_t, and how that relates to your code.

That one was for McGyver As you say useless in my code.



usleep and sleep are both (generally) implemented as calls to nanosleep with a suitably multiplied input amount of time. (e.g. usleep is essentially nanosleep(time * 1000) [yes, I know, that's not the right way to call nanosleep].

Originally Posted by matsp

So calling sleep followed by usleep won't really make much sense.

In this case maybe not, but what if you want to make a 1.25 second sleep? usleep uses usecond_t variables. And the type useconds_t is an unsigned integral capable of storing values at least in the range zero to 1,000,000 that's from 0 to 1 sec I think.

--
Mats[/QUOTE]

Originally Posted by bartleby84

That one was for McGyver As you say useless in my code.



usleep and sleep are both (generally) implemented as calls to nanosleep with a suitably multiplied input amount of time. (e.g. usleep is essentially nanosleep(time * 1000) [yes, I know, that's not the right way to call nanosleep].



In this case maybe not, but what if you want to make a 1.25 second sleep? usleep uses usecond_t variables. And the type useconds_t is an unsigned integral capable of storing values at least in the range zero to 1,000,000 that's from 0 to 1 sec I think.

--
Mats

[/QUOTE]

If you wanted a 1.25 second sleep, you'd call sleep with 1250 as an argument, clearly.. One second = 1000 milliseconds.

Originally Posted by MacGyver

The sleep() family of functions have nothing to do with time_t.

So....

What is the issue again?

I first tried to use the nanoleep() function that need a timespec struture and this structure has two variables, one is a long to represent the nanosecs (from 0 to 1 sec) an the other one to represent the secs is a time_t variable.

Originally Posted by matsp

If you want to sleep 1.25 seconds, you specify 1250000 ((int)(1.25 * 1e6) if you want it as a calculation, or 1250 * 1000 for integer, where 1250 is the number of milliseconds you want to sleep) to usleep. useconds_t is certainly a 32-bit integer if it's not larger, so you should be fine up to about 2000 seconds at least.

--
Mats

Thats is new for me I read from http://www.opengroup.org/onlinepubs/...s/types.h.html that useconds_t has a limited range. There was my problem.

I tried to make a usleep(2000000) and it works.