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<?php $x = 3.4; //float var_dump($x); $tmp = $x; var_dump($tmp); $tmp = array($x); var_dump($tmp); /* array (size=1) 0 => float 3.4 */ $tmp = array(array($x)); var_dump($tmp); /* array ( 0 => array ( 0 => 3.3999999999999999, ), ) */
Output for 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 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 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
float(3.4) float(3.4) array(1) { [0]=> float(3.4) } array(1) { [0]=> array(1) { [0]=> float(3.4) } }

preferences:
127.89 ms | 408 KiB | 5 Q