utility.cpp

VC源代码大全（精华版）

//
//	utility.cpp. Some useful routines to make life easier
//
#include "stdafx.h"

void Randomize ()
{
time_t		t;
unsigned int	n;

/*
	Get the current time. That will be used to seed the random number
	function.
 */
	time (&t);

/*
	srand() requires an unsigned int, but time returns an unsigned long.
	Mask off any unused bits at the top in case there are any errors
	in typecasting (we want the lower part of the time because it should
	always be different, and sizeof (time_t) and sizeof (int) may not be
	the same on all systems).
 */
	n = (unsigned int) (t & ((long) ((unsigned int) -1)));

/*
		Now, use that value as the random number seed.
 */
	srand (n);
}

/*
	Return a random number in the range 0 to num-1. If 0 is passed, return
	it. If a negative number is passed, return the random number.
 */

int Random (int num)
{
	if (!num)
		return (0);
	if (num < 0)
		return (rand ());
	return (rand () % num);
}