Thread: How to execute a command every specific,randomly time?

Lets say I want within my program to execute a statement/function every couple of random times?
like executing some function between 3-5 seconds elpased within runtime of the program (with cycling too, not only once).
Im using borland turbo C++ in a graphics.h (bgi) project and need to put a BLOCK of rectangles every couple of seconds to block the moving "pacman" . Thats the last thing remained for me and I donno how to do it. I can make the Block appear and go away by the putimage(.........,COPY_PUT) and then putimage(.....,XOR_PUT).
What I do not know is how I can execute them randomly or constantly every couple of secs.
Thanks

a simpler way to do it (but possibly harder to code for some people) would be to have a loop like this

PHP Code:

while(gameon == true)
{
       if(rand()%10 == 3) //this will occur about 1/10th of the time
       {
              do_rect_stuff();  //stuff to be done rarely
       }
       do_other_stuff(); //stuff to be done each turn
} 


of course if you wanted a different percent you could change the %10 after rand to give you better (or worse) odds

hope this helps