Online PHP editor | refs for sYolO

<?php var_dump(is_numeric('1')); echo (1 ** '1') . "\n"; var_dump(is_numeric('1')); echo (2 ** '1.') . "\n"; var_dump(is_numeric('1.')); echo (3 ** '+1.0') . "\n"; var_dump(is_numeric('+1.0')); echo (4 ** '+1.0e') . "\n"; var_dump(is_numeric('+1.0e')); echo (5 ** '+1.0e0') . "\n"; var_dump(is_numeric('+1.0e0')); echo (6 ** '+1.0e0 ') . "\n"; var_dump(is_numeric('+1.0e0 ')); echo (7 ** '+1.0e0 x') . "\n"; var_dump(is_numeric('+1.0e0 x'));