PHP implements half query algorithm

PHP implements the half query algorithm and you write the code yourself, which may not be standardized.

What is the half query algorithm? Describe yourself in Baidu with specific words. Directly upload the code:

<?php
header("Content-type: text/html; charset=utf-8"); 

/* 折半查询算法--不用递归 */
function qSort($data = array(), $x = 0){
	$startIndex = 0;                // 开始索引
	$endIndex = count($data) - 1;   // 结束索引
	$index = 0;
	$number = 0;                    // 计数器
	do{
		if($endIndex > $startIndex){
			$searchIndex = ceil(($endIndex - $startIndex) / 2);
		}else if($endIndex == $startIndex){
			$searchIndex = $endIndex;
		}else{
			$index = -1;
			break;
		}
		$searchIndex += ($startIndex - 1);

		echo '检索范围：'.$startIndex.' ~ '.$endIndex.'<br>检索位置：'.$searchIndex.'检索值为：'.$data[$searchIndex];
		echo '<br>=======================<br><br>';

		if($data[$searchIndex] == $x){
			$index = $searchIndex;
			break;
		}else if($x > $data[$searchIndex]){
			$startIndex = $searchIndex + 1;
		}else{
			$endIndex = $searchIndex - 1;
		}

		$number++;
	}while($number < count($data));
	return $index;
}

/* 折半查询算法--使用递归 */
function sSort($data, $x, $startIndex, $endIndex){
	if($endIndex > $startIndex){
		$searchIndex = ceil(($endIndex - $startIndex) / 2);
	}else if($endIndex == $startIndex){
		$searchIndex = $endIndex;
	}else{
		return -1;
	}

	$searchIndex += ($startIndex - 1);

	echo '检索范围：'.$startIndex.' ~ '.$endIndex.'<br>检索位置：'.$searchIndex.'检索值为：'.$data[$searchIndex];
	echo '<br>=======================<br><br>';

	if($data[$searchIndex] == $x){
		return $searchIndex;
	}else if($x > $data[$searchIndex]){
		$startIndex = $searchIndex + 1;
		return sSort($data, $x, $startIndex, $endIndex);
	}else{
		$endIndex = $searchIndex - 1;
		return sSort($data, $x, $startIndex, $endIndex);
	}
}

$data = array(1, 3, 4, 6, 9, 11, 12, 13, 15, 20, 21, 25, 33, 34, 35, 39, 41, 44);

$index = qSort($data, 11);                       // 不用递归的排序方法
$index = sSort($data, 11, 0, count($data) - 1);  // 使用递归的排序方法
echo '结果：'.$index;

The above introduces the implementation of the half query algorithm in PHP, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.