I want to sleep in a C11 program. Neither usleep (in unistd.h) nor nanosleep (in time.h) are declared with the -std=c11
option of both gcc (4.8.2) and clang (3.2).
A grep sleep /usr/include/*.h
doesn't reveal any other likely sleep candidates.
I need a sleep with at least millisecond precision.
How do I sleep in C11?
The function sleep gives a simple way to make the program wait for a short interval. If your program doesn't use signals (except to terminate), then you can expect sleep to wait reliably throughout the specified interval.
h> , and use this function for pausing your program execution for desired number of seconds: sleep(x); x can take any value in seconds.
The sleep() function suspends (waits) execution of the current thread for a given number of seconds. Python has a module named time which provides several useful functions to handle time-related tasks. One of the popular functions among them is sleep() .
sleep() function is provided by unistd. h library which is a short cut of Unix standard library.
Use -std=gnu11
instead of -std=c11
(this works for both clang and gcc). This will cause the <time.h>
header to define nanosleep
.
Another alternative to nanosleep
, calling pselect
on a null file descriptor with a timeout, also only works with -std=gnu11
and not -std=c11
For an example of both:
#include <stdio.h>
#include <sys/select.h>
int main() // Compile with -std=gnu11 (and not -std=c11)
{
struct timespec ts1 = {
.tv_sec = 0,
.tv_nsec = 500*1000*1000
};
printf("first\n");
nanosleep(&ts1, NULL);
printf("second\n");
pselect(0, NULL, NULL, NULL, &ts1, NULL);
printf("third\n");
}
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