PHP7 introduced '? ? 'And'? Explain the difference between: '
- 2021-12-04 18:25:04
- OfStack
Practice brings true knowledge ~
Test code
Input test:
<?php
$array = [
'a' => 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);
Output:
PHP Notice: Undefined index: d in /home/fanyu/abc.php on line 11
PHP Notice: Undefined index: d in /home/fanyu/abc.php on line 14
array(0) {
}
int(0)
int(0)
int(0)
int(0)
int(1)
int(0)
int(0)
int(0)
int(0)
Conclusion
$a? ? 0 is equivalent to isset ($a)? $a: 0. $a? : 0 equals $a? $a: 0. empty: Determines whether a variable is null (null, false, 00, 0, '0', "true will be returned). isset: Determines whether a variable is set (values are false, 00, 0, '0', "true will also be returned).Summarize