array_keys

(PHP 4 )

array_keys -- Return all the keys of an array

Description

array array_keys ( array input [, mixed search_value])

array_keys() 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.

範例 1. array_keys() example

$array = array (0 =  100, "color" =  "red");
print_r(array_keys ($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 printout of the program above will be:

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




注: This function was added to PHP 4, below is an implementation for those still using PHP 3.

範例 2. Implementation of array_keys() for PHP 3 users

function array_keys ($arr, $term="") {
    $t = array();
    while (list($k,$v) = each($arr)) {
        if ($term    $v != $term) {
            continue;
        }
        $t[] = $k;
    }
    return $t;
}


See also array_values().