Online PHP editor | perf for NlsF9

<?php function is_palindrome($str) { $len = strlen($str); if ($len < 2) { // strings of 0 or 1 characters are palindromes return true; } elseif ($str[0] != $str[$len-1]) { // first character doesn't match last character, so not a palindrome return false; } else { // first character is equal to last character, // so see if the rest of the string is a palindrome return is_palindrome(substr($str, 1, $len - 2)); } } foreach (['rotor', 'a', 'deed', 'hello', 'xyyz'] as $str) { echo "\"$str\" is" . (is_palindrome($str) ? "" : " not") . " a palindrome\n"; } function is_palindrome_broken($str) { $len = strlen($str); if ($len < 2) { // strings of 0 or 1 characters are palindromes return true; } elseif ($str[0] != $str[$len-1]) { // first character doesn't match last character, so not a palindrome return false; } else { // first character is equal to last character, // so see if the rest of the string is a palindrome is_palindrome_broken(substr($str, 1, $len - 2)); } } foreach (['rotor', 'a', 'deed', 'hello', 'xyyz'] as $str) { echo "\"$str\" is" . (is_palindrome_broken($str) ? "" : " not") . " a palindrome\n"; }

Version	System time (s)	User time (s)	Memory (MiB)
8.3.6	0.013	0.007	16.63
8.3.5	0.009	0.006	20.03
8.3.4	0.010	0.003	21.71
8.3.3	0.011	0.007	19.07
8.3.2	0.008	0.000	24.18
8.3.1	0.000	0.007	24.66
8.3.0	0.007	0.000	26.16
8.2.18	0.004	0.011	25.92
8.2.17	0.011	0.004	18.96
8.2.16	0.003	0.010	22.96
8.2.15	0.007	0.000	25.66
8.2.14	0.000	0.007	24.66
8.2.13	0.004	0.004	26.16
8.2.12	0.000	0.007	19.79
8.2.11	0.009	0.000	20.52
8.2.10	0.009	0.000	20.39
8.1.28	0.011	0.003	25.92
8.1.27	0.004	0.004	23.99
8.1.26	0.004	0.004	26.35
8.1.25	0.000	0.008	28.09
8.1.24	0.006	0.003	18.66
8.1.23	0.003	0.009	18.38
8.1.6	0.003	0.005	17.57