php array_keys returns the key name of the array in detail

The array_keys function in php is used to return a new array containing all the key names in the array. This article introduces in detail how to use the PHP array_keys function. Coders who need it can refer to

array_keys returns some or all key names in the array

Instructions

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

array_keys() Returns the number or string key in the $array array name.

If the optional parameter search_value is specified, only the key name of the value will be returned. Otherwise all keys in the $array array will be returned.

Detailed explanation of parameters

Parameters	Description
array	Required. An array containing the keys to be returned.
search_value	Optional. If this parameter is specified, only keys containing these values ​​will be returned.
strict	Optional. Used with the value parameter. Possible values: #true - Returns the key name with the specified key value. Depending on the type, the number 5 is not the same as the string "5". false - Default value. Independent of type, the number 5 is the same as the string "5".

Return value

Returns all keys in array.

Example

<?php
$array = array( 0 => 100 , "color" => "red" );
 print_r ( array_keys ( $array ));

 $array = array( "blue" , "red" , "green" , "blue" , "blue" );
 print_r ( array_keys ( $array , "blue" ));

 $array = array( "color" => array( "blue" , "red" , "green" ),
        "size"  => array( "small" , "medium" , "large" ));
 print_r ( array_keys ( $array ));
 ?>

The above routine will output:

Array ( [0] => 0 [1] => color ) Array ( [0] => 0 [1] => 3 [2] => 4 ) Array ( [0] => color [1] => size )

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