Have a function run for a specific amount of time in C

Question

I need to be able to run a piece of code for x amount of seconds and then stop. Something like

while(timeElapsed < setTime){
     do whatever
}

If someone is curious, what is we're trying to do here is having the program poll an indicator via modbus for a certain amount of seconds, set by the user.So I'm having an input field for the user to set the time the polling function should be running in a loop. This will be done on a raspberry pi, by the way.

Answer 1

One way is to include time.h header and use difftime function. It will be implemented to check if the elaspsed time reaches the set time.

example:

#include <time.h>

void func(float delayInSeconds) {
    time_t startTime;
    time_t now;
    float elapsedTime;
    float setTime = delayInSeconds;

    time(&startTime);
    while (elapsedTime < setTime) {
        //do something...

        now = time(NULL);
        elapsedTime = difftime(now, startTime);
    }
}