Here is a puzzle from me.
What does this code do?

    for(ii = 0; ii < 5; ii++)
    {
	xx[ii] = 0;
    }

    while(var--)
    {
	if(++xx[0] == 10)
	{
            xx[0] = 0;
	    if(++xx[1] == 10)
	    {
                xx[1] = 0;
                if(++xx[2] == 10)
                {
                    xx[2] = 0;
                    if(++xx[3] == 10)
                    {
                        xx[3] = 0;
                        xx[4]++;
                    }
                }
            }
        }
    }