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PHP array_keys() Function

PHP Array Reference Complete PHP Array Reference

Definition and Usage

The array_keys() function returns an array containing the keys.

Syntax

array_keys(array,value)

Parameter Description
array Required. Specifies an array
value Optional. You can specify a value, then only the keys with this value are returned
strict Optional. 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".

Example 1

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

The output of the code above will be:

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

Example 2

Using the value parameter.

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

The output of the code above will be:

Array ( [0] => c)

Example 3

Using the strict parameter: false

<?php
$a=array(10,20,30,"10");
print_r(array_keys($a,"10",false));
?>

The output of the code above will be:

Array ( [0] => 0 [1] => 3 )

Example 4

Using the strict parameter: true

<?php
$a=array(10,20,30,"10");
print_r(array_keys($a,"10",true));
?>

The output of the code above will be:

Array ( [0] => 3)

PHP Array Reference Complete PHP Array Reference
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