$a = 0; $b = "0"; $c = ""; $d = false; $e = null; $f = []; $g = array(); echo $a?"0 is true":"0 is false \n"; echo $b?"'0' is true":"'0' is false \n"; echo $c?"'' is true":"'' is false \n"; echo $d?"false is true":"false is false \n"; echo $e?"null is true":"null is false \n"; echo $f?"[] is true":"[] is false \n"; echo $g?"array() is true":"array() is false \n"; echo $f===$g?"[] === array() \n":"[] !== array() \n";
运行结果：
0 is false '0' is false '' is false false is false null is false [] is false array() is false [] === array()
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