(PHP 7 >= 7.3.0, PHP 8)
array_key_last — Gets the last key of an array
Get the last key of the given array without affecting
the internal array pointer.
arrayAn array.
Returns the last key of array if the array is not empty;
null otherwise.
For PHP <= 7.3.0 :
if (! function_exists("array_key_last")) {
function array_key_last($array) {
if (!is_array($array) || empty($array)) {
return NULL;
}
return array_keys($array)[count($array)-1];
}
}For those who loves tested candies;
<?php
function array_key_last(array $array) {
// 100000 iters: ~0.068 secs
return key(array_slice($array, -1));
// 100000 iters: ~0.070 secs
return key(array_reverse($array));
// 100000 iters: ~0.088 secs
return array_keys($array)[count($array) - 1] ?? null;
}
?>Try to beat this polyfill in terms of performance!
<?php
if( !function_exists('array_key_last') ) {
function array_key_last(array $array) {
if( !empty($array) ) return key(array_slice($array, -1, 1, true));
}
}
// Bonus
if (!function_exists('array_key_first')) {
function array_key_first(array $arr) {
foreach($arr as $key => $unused) return $key;
}
}
?><?php
// PHP >= 7
function _array_key_last(array $array){
return (!empty($array)) ? array_keys($array)[count($array)-1] : null;
}
var_dump(_array_key_last(['PHP', 'Javascript', 'Python'])); // 2
?>Notice!
$a = array(
1 => 1,
0 => 0
);
echo (array_key_last($a)); // output: "0", not "1"// if : php ver < 7
// array_key_last
$arr = array('1'=>'bear1','2'=>array('22'=>'bear22'),'3'=>'bear3');
echo end(array_keys($arr));
// result : 3https://www.php.net/manual/fr/function.array-key-last.php#123950
did return the first key of my array only:
"array_keys($array)[count($array) - 1] ?? null" works
I hope the example is fine for everyone else.
My array is:
[
new NameExpression('d', 0),
new NameExpression('f', 0),
new NameExpression('g', 0),
]For PHP < 7.3.0 :
Will work for any type of array
<?php
if ( ! function_exists( 'array_key_last' ) ) {
/**
* Polyfill for array_key_last() function added in PHP 7.3.
*
* Get the last key of the given array without affecting
* the internal array pointer.
*
* @param array $array An array
*
* @return mixed The last key of array if the array is not empty; NULL otherwise.
*/
function array_key_last( $array ) {
$key = NULL;
if ( is_array( $array ) ) {
end( $array );
$key = key( $array );
}
return $key;
}
}
?>Now that we have this function, where we once used...
<?php
$idxLast = count($arr) - 1;
?>
we can now optimize code speed by using...
<?php
$idxLast = (array_key_last($arr) ?? 0);
?>
Use-cases include lots of looping and control-structures.
If you do not know ahead of time that the array is numerically indexed, and that it could possibly be associative...safer/faster to stick with count().This polyfill works for PHP 5.6+.
It is a slight modification of "wes at nospam dot example dot org"'s example:
<?php
if( !function_exists('array_key_first') ) {
function array_key_first(array $array) {
if( $array === [] ) { return NULL; }
foreach($array as $key => $_) { return $key; }
}
}
if( !function_exists('array_key_last') ) {
function array_key_last(array $array) {
if( $array === [] ) { return null; }
// the last 2 args to array_slice are crucial
return array_key_first(array_slice($array, -1, null, true));
}
}Here come my benchmark, and
return key(array_slice($array, -1));
is the my best answer for a polyfill.
<?php
function array_key_last_1(array $array) {
// assert(!empty($array));
return key(array_slice($array, -1));
}
function array_key_last_2(array $array) {
return key(array_slice($array, -1, 1, true));
}
function array_key_last_3(array $array) {
return key(array_reverse($array));
}
function array_key_last_4(array $array) {
return array_keys($array)[count($array) - 1] ?? null;
}
function array_key_last_5(array $array) {
return array_keys($array)[count($array) - 1] ?? null;
}
function array_key_last_6(array $array) {
$copy = array_keys($array);
return end($copy);
}
$result = array();
$array = range(0, 1000000);
for($i=1; $i < 7;$i++) {
$callback = 'array_key_last_' . $i;
$before = microtime(true);
call_user_func_array($callback, array($array));
$after = microtime(true);
$time = ($after-$before);
$result[$callback] = $time;
}
asort($result);
foreach ($result as $key => $value) {
echo '[' . $key . ']' . $value . " sec" . PHP_EOL;
}Correct polyfill (one that doesn't make copies of arrays, and that doesn't make use of the IAP) is:
<?php
if(!function_exists('array_key_first')){
function array_key_first(array $array){
if($array === []){
return NULL;
}
foreach($array as $key => $_) return $key;
}
}
if(!function_exists('array_key_last')){
function array_key_last(array $array){
if($array === []){
return NULL;
}
return array_key_first(array_slice($array, -1));
}
}
?>