PHP Array_keys ()

Definition and usage

The Array_keys () function returns a new array that contains all the key names in the array.

If the second argument is supplied, only the key name of the value is returned.

If the strict parameter is specified as true, PHP uses the congruent comparison (= = =) to strictly check the data type of the key value.

Grammar

Array_keys (Array,value)

Parameters	Describe
Array	Necessary. Specifies the input array.
Value	Optional. The index (key) of the specified value.
Strict	Optional. Used with the value parameter. Possible values: True-Returns the key name with the specified value, based on the type. False-The default value. Does not depend on the type.

Example 1

Use the strict parameter (false):

<?php$a = Array (10,20,30, "ten");p Rint_r (Array_keys ($a, "ten", false)); >

Output:

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

Example 2

Use the strict parameter (true):

<?php$a = Array (10,20,30, "ten");p Rint_r (Array_keys ($a, "ten", true)); >

Output:

Array ([0] = 3)

　　

PHP Array_keys ()