Using the "??" operator in PHP7

How to use the "??" operator in PHP7? The following article will introduce to you the usage of "??" in PHP7. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

?? operator in PHP7, let’s take a look at its specific function

?? is equivalent to

isset($a)? $a :$b;

Determine whether a variable a exists. If it exists, assign variable a. If it does not exist, assign variable b

Note that it is to determine whether a variable exists, not to determine whether a variable is empty

Look at the code directly

$a = $a ?? 1;
var_dump($a);//1

$a = 5;
$a = $a ?? 1;
var_dump($a);//5

$a = 0;
$a = $a ?? 1;
var_dump($a);//0

This article is reproduced from: https://blog.csdn.net/kelinfeng16/article/details/103111710

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