Time function for game in C

Hi,
Im developing a game in which the user puts some value of time between 5 and 15 seconds for each play. The game should run until the time reaches its end (value inserted by the user). I’ve not been able to code thi, I’ve tried wait(), diff_time, sleep() but those didn’t work out since sleep() actually stops the processes entirely. What I’m trying to say is, is there a function of time that can run in “background” and when the time ends return some value that I can use for... let’s say an if statement, run the game until that value is returned.
Thank you everyone.

Which OS and Compiler are you using?

Maybe what you are looking for is something like this:

Code:

---

#include <time.h>

// 15 seconds...
#define DELTA_TIME 15

extern void scheduled_task( void );
extern void game_logic( void );

void main( void )
{
  time_t start, current;

  // Game Main Loop.
  start = time(NULL);
  for (;;)
  {
    current = time(NULL);
    if ( current - start >= DELTA_TIME )
    {
      scheduled_task();
      start = current;
    }

    game_logic();
  }
}

---

I’m using Mac OS X and XCODE

If you want to use a callback, you can always use SIGALRM signal. But SIGALRM can be used by sleep() in cerain Unix implementations (I don't know about OS/X).. And you may have problems with some libc functions that aren't "signal safe" (take a look at glibc documenation).