??是PHP7版本的新特性,它与?:的区别在哪里呢?
??
$b = $a?? $c ;相当于$b= isset($a)?$a:$c;
?:
$b = $a?$a: $c 则是 $b = !empty($a) ? $a:$c;
??是PHP7版本的新特性,它与?:的区别在哪里呢?
$b = $a?? $c ;相当于$b= isset($a)?$a:$c;
$b = $a?$a: $c 则是 $b = !empty($a) ? $a:$c;
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