How to find the maximum subscript in an array in php

php Steps to find the maximum subscript in an array: 1. Use the array_keys() function to obtain all subscripts in the array, and return the obtained array subscript in array form, with the syntax "array_keys (original array)", An array containing all subscripts will be returned; 2. Use the max() function to obtain the maximum value in the subscript array, with the syntax "max (subscript array)".

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

In PHP, form the subscript of the array For an array, the maximum subscript can be obtained through the max function.

Implementation steps:

1. Use the array_keys function to form all the subscripts of the array into an array

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);  
$arr=array("1"=>5,"8"=>7,"3"=>4,"7"=>5,"6"=>5);
var_dump($arr);
$key=array_keys($arr);
var_dump($key);
?>

2. Use the max function to obtain the maximum value of the subscript array

max() can obtain the maximum value of an array.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);  
$arr=array("1"=>5,"8"=>7,"3"=>4,"7"=>5,"6"=>5);
var_dump($arr);
$key=array_keys($arr);
var_dump($key);

$res=max($key);
echo "最大下标为：".$res;
?>

Explanation:

In PHP, each element of the array is composed of key-value pairs. key (subscript) to access the value of the corresponding key (subscript).

The array_key() function can obtain some or all key names in the array. The syntax format of this function is as follows:

array_keys($array [, $search_value = null [, $strict = false]])

The parameter description is as follows:

• $array: required parameter, which is the array to be operated;
• $search_value: optional parameter, if the parameter is empty, the function will return all key names in the array, if this parameter is specified, then The function will only return the key name with the value $search_value;
• $strict: Optional parameter to determine whether to use strict mode when searching. $strict defaults to false, which is non-strict mode. When searching Only types are compared, not types. If $strict is set to true, that is strict mode, the value and type are compared at the same time during search, which is equivalent to ===.

array_key() function will return the obtained array key name (subscript) in the form of an array.

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