PHP array_keys() Function

PHP array_keys() Function

The array_keys() function  in PHP is used to return all the keys, numeric and string from the given array.

Syntax

array_keys ( array $array )

or

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

Parameter

array(required)- This parameter specifies the input array

search_value(optional)- This parameter specifies a value, where only the keys with this value are returned.

strict(optional)- This parameter takes Boolean value. The possible value are as follows:

• If True is passed, it returns the keys with the specified value, depending on the type.
• If passed False (default value), it returns the keys with the specified value, not depending on the type

Return

This function returns an array containing all the keys present in the array.

Example 1

Output

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

Example 2

Output

Array
 (
     [0] => 3
 ) 

Example 3

"Reema","Student2"=>"Varun","Student3"=>"Rahul","Student4"=>"Avijit");
 print_r(array_keys($array,"Reema"));
 ?> 

Output

Array
 (
     [0] => Student1
 ) 

Example 4

 array("Java", "PHP", "Python"),
                "size"  => array("small", "medium", "large"));
 print_r(array_keys($array));
 ?> 

Output

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