PHP - Function array_keys()


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Syntax

array_keys ( $input [, $search_value [, $strict]] );

Definition and Usage

Returns the keys, numeric and string, from the input array. If the optional search_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the input are returned.

Parameters

ParameterDescription
inputRequired.Specifies an array.
search_valueRequired. You can specify a value, then only the keys with this value are returned.
strictOptional. Used with the value parameter. Possible values:

* true - Returns the keys with the specified value, depending on type: the number 5 is not the same as the string "5".

* false - Default value. Not depending on type, the number 5 is the same as the string "5".

Return Values

Returns the keys, numeric and string, from the input array

Example

Try out following example:

<?php
$a=array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_keys($a));
$a=array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_keys($a,"Dog"));
$a=array(10,20,30,"10");
print_r(array_keys($a,"10",false));
?> 

This will produce following result:

Array 
(
   [0] => a
   [1] => b 
   [2] => c
)
Array 
(
   [0] => c
)
Array
(
   [0] => 0
   [1] => 3
)

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