php 二分查找法算法详解

header("Content-type:text/html;charset='utf-8'");
function twosearchmethod($arr,$val,$left,$right){
	if($left>$right){
		echo "找不到该数值";
		return ;
	}
	$middle=round(($left+$right)/2);
	if($arr[$middle]>$val){
		twosearchmethod($arr, $val, $left, $middle-1);
	}elseif($arr[$middle]<$val){
		twosearchmethod($arr, $val, $middle+1, $right);
	}else{
		echo $middle;
	}
	
}
$arr=array(1,9,3,4,5,6,7);
sort($arr);
print_r($arr);
echo "<br/>";
$val=1;
twosearchmethod($arr, $val, 0, 6);