You see it as pausing your program, but what they really do is release the CPU for that amount of time. Sleep(), usleep(), nanosleep() have a hidden benefit. See man 2 time, man gettimeofday, man clock_gettime. Making a timer works the same way except when you add your time to wait you need to remember to manually do the carry (into the time_t) if the resulting microseconds or nanoseconds value goes over 1 second. For times less than 1 second you need to use gettimeofday() (microseconds) or clock_gettime() (nanoseconds) and deal with a struct timeval or struct timespec which is a time_t and the microseconds or nanoseconds since that 1 second mark. That will probably include resetting it by doing another fire_t = time(NULL) + seconds_to_wait for next time.Ī time_t is a somewhat antiquated unix method of storing time as the number of seconds since midnight but it has many advantages.

If (my_t > fire_t) then consider the timer fired and do the stuff you want there. Inside your loop do another my_t = time(NULL) A time_t is essentially a uint32_t, you may need to cast it. Then (for times over 1 second), initialize your timer by reading the current time: my_t = time(NULL) Īdd the number of seconds your timer should wait and store it in fire_t. If you already have a main loop (most GUI event-driven stuff does) you can probably stick your timer into that.

Codevision timer examples