3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array['4e3'] = 'string'; $array['4e100'] = 'string'; $array['4e+3'] = 'string'; $array['4E+4'] = 'string'; $array['4.1'] = 'string'; $array['4'] = 'string'; $array['0123'] = 'string'; var_dump($array);
Output for 7.0.0 - 7.0.24, 7.1.0 - 7.1.20, 7.2.6 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array(7) { ["4e3"]=> string(6) "string" ["4e100"]=> string(6) "string" ["4e+3"]=> string(6) "string" ["4E+4"]=> string(6) "string" ["4.1"]=> string(6) "string" [4]=> string(6) "string" ["0123"]=> string(6) "string" }

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153.96 ms | 404 KiB | 174 Q