PHP Numeric strings

String PHP dianggap numerik jika dapat diinterpreted sebagai int atau float. Secara resmi pada PHP 8.0.0:

WHITESPACES      \s*
LNUM             [0-9]+
DNUM             ([0-9]*)[\.]{LNUM}) | ({LNUM}[\.][0-9]*)
EXPONENT_DNUM    (({LNUM} | {DNUM}) [eE][+-]? {LNUM})
INT_NUM_STRING   {WHITESPACES} [+-]? {LNUM} {WHITESPACES}
FLOAT_NUM_STRING {WHITESPACES} [+-]? {EXPONENT_DNUM} {WHITESPACES}
NUM_STRING       ({INT_NUM_STRING} | {FLOAT_NUM_STRING})

PHP juga memiliki konsep leading numeric string. Ini hanyalah string yang dimulai seperti string numerik diikuti oleh karakter apa pun.

<?php
$foo = 1 + "10.5";                // $foo is float (11.5)
$foo = 1 + "-1.3e3";              // $foo is float (-1299)
$foo = 1 + "bob-1.3e3";           // TypeError as of PHP 8.0.0, $foo is integer (1) previously
$foo = 1 + "bob3";                // TypeError as of PHP 8.0.0, $foo is integer (1) previously
$foo = 1 + "10 Small Pigs";       // $foo is integer (11) and an E_WARNING is raised in PHP 8.0.0, E_NOTICE previously
$foo = 4 + "10.2 Little Piggies"; // $foo is float (14.2) and an E_WARNING is raised in PHP 8.0.0, E_NOTICE previously
$foo = "10.0 pigs " + 1;          // $foo is float (11) and an E_WARNING is raised in PHP 8.0.0, E_NOTICE previously
$foo = "10.0 pigs " + 1.0;        // $foo is float (11) and an E_WARNING is raised in PHP 8.0.0, E_NOTICE previously
?>

Source code project ini dapat di download di Github php-tutorial