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<?php error_reporting(0); echo 'null == false? ', (null == false) ? 'yes' : 'no', "\n"; echo 'null == 0 ? ', (null == 0) ? 'yes' : 'no', "\n"; echo 'null == "0" ? ', (null == "0") ? 'yes' : 'no', "\n"; echo 'null == $foo ? ', (null == $foo) ? 'yes' : 'no', "\n"; echo 'null == "" ? ', (null == "") ? 'yes' : 'no', "\n"; echo 'false == 0 ? ', (false == 0) ? 'yes' : 'no', "\n"; echo 'false == "0" ?', (false == "0") ? 'yes' : 'no', "\n"; echo 'false == $foo ? ', (false == $undefined) ? 'yes' : 'no', "\n"; echo 'false == "" ? ', (false == "") ? 'yes' : 'no', "\n"; echo '0 == "0" ? ', (0 == "0") ? 'yes' : 'no', "\n"; echo '0 == $foo ? ', (0 == $undefined) ? 'yes' : 'no', "\n"; echo '0 == "" ? ', (0 == "") ? 'yes' : 'no', "\n"; echo '"0" == $foo ? ', ("0" == $undefined) ? 'yes' : 'no', "\n"; echo '"0" == "" ? ', ("0" == "") ? 'yes' : 'no', "\n"; echo '$foo == "" ? ', ($undefined == "") ? 'yes' : 'no', "\n";
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
null == false? yes null == 0 ? yes null == "0" ? no null == $foo ? yes null == "" ? yes false == 0 ? yes false == "0" ?yes false == $foo ? yes false == "" ? yes 0 == "0" ? yes 0 == $foo ? yes 0 == "" ? no "0" == $foo ? no "0" == "" ? no $foo == "" ? yes
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.36, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
null == false? yes null == 0 ? yes null == "0" ? no null == $foo ? yes null == "" ? yes false == 0 ? yes false == "0" ?yes false == $foo ? yes false == "" ? yes 0 == "0" ? yes 0 == $foo ? yes 0 == "" ? yes "0" == $foo ? no "0" == "" ? no $foo == "" ? yes

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214.46 ms | 405 KiB | 375 Q