Example analysis of the difference between '??' and '?:' introduced in PHP7-PHP7-php.cn

Example analysis of the difference between '??' and '?:' introduced in PHP7

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Release： 2023-02-17 16:50:01

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Example analysis of the difference between '??' and '?:' introduced in PHP7

##Practice brings true knowledge~

Test code

Input test:

 1,
        'b' => 2,
        'c' => [],
    ];

    $a = $array['c'] ?? 0;
    $b = $array['c'] ?: 0;
    $c = $array['d'] ?? 0;
    $d = $array['d'] ?: 0;
    $e = $array['c'] ? 1 : 0;
    $f = isset($array['c']) ? 1 : 0;
    $g = $array['d'] ? 1 : 0;
    $h = isset($array['d']['e']) ? 1 : 0;
    $i = !empty($array['c']) ? 1 : 0;
    $j = !empty($array['d']) ? 1 : 0;

    var_dump($a);
    var_dump($b);
    var_dump($c);
    var_dump($d);
    var_dump($e);
    var_dump($f);
    var_dump($g);
    var_dump($h);
    var_dump($i);
    var_dump($j);

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Output result:

PHP Notice:  Undefined index: d in /home/fanyu/abc.php on line 11PHP Notice:  Undefined index: d in /home/fanyu/abc.php on line 14array(0) {}int(0)int(0)int(0)int(0)int(1)int(0)int(0)int(0)int(0)

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Conclusion

$a ?? 0 Equivalent to isset($a) ? $a: 0.
$a ?: 0 is equivalent to $a ? $a : 0.
empty: Determine whether a variable is empty (null, false, 00, 0, '0', ‖ and the like will all return true).
isset: Determine whether a variable is set (values such as false, 00, 0, '0', ‖ will also return true).

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