/**
 * PHP实现二分查找算法
 *
 * @param 
 * @author 编程之家 jb51.cc jb51.cc
 **/
// $low and $high have to be integers
function BinarySearch( $array,$key,$low,$high )
{
	if( $low > $high ) // termination case
	{
		return -1;
	}
	$middle = intval( ( $low+$high )/2 ); // gets the middle of the array
	if ( $array[$middle] == $key ) // if the middle is our key
	{
		return $middle;
	}
	elseif ( $key < $array[$middle] ) // our key might be in the left sub-array
	{
		return BinarySearch( $array,$middle-1 );
	} 
	return BinarySearch( $array,$middle+1,$high ); // our key might be in the right sub-array
}
/***   来自编程之家 jb51.cc（jb51.cc）   ***/