[英]PHP Null coalescing operator confusion
I'm a bit confused. 我有点困惑。 The PHP documenation says:
PHP文档指出:
// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';
// The above is identical to this if/else statement
if (isset($_POST['action'])) {
$action = $_POST['action'];
} else {
$action = 'default';
}
But my own example says something very different: 但是我自己的例子却说出了非常不同的东西:
echo "<pre>";
$array['intValue'] = time();
$array['stringValue'] = 'Hello world!';
$array['boolValue'] = false;
$resultInt = isset($array['intValue']) ?? -1;
$resultString = isset($array['stringValue']) ?? 'Another text';
$resultBool = isset($array['boolValue']) ?? true;
var_dump($resultInt);
var_dump($resultString);
var_dump($resultBool);
echo '<br/>';
if(isset($array['intValue'])) $_resultInt = $array['intValue'];
else $_resultInt = -1;
if(isset($array['stringValue'])) $_resultString = $array['stringValue'];
else $_resultString = 'Another text';
if(isset($array['boolValue'])) $_resultBool = $array['boolValue'];
else $_resultBool = true;
var_dump($_resultInt);
var_dump($_resultString);
var_dump($_resultBool);
echo "</pre>";
My output: 我的输出:
bool(true)
bool(true)
bool(true)
int(1534272962)
string(12) "Hello world!"
bool(false)
So, as my example shows, the if-condition does not result in the same as the null coalescing operator does as the documentation says. 因此,如我的示例所示,if条件与文档中所说的空合并运算符的结果不同。 Can somebody explain me, what I did wrong?
有人可以解释我,我做错了什么吗?
Thank you! 谢谢!
You're doing: 你在做:
$resultInt = isset($array['intValue']) ?? -1;
$resultString = isset($array['stringValue']) ?? 'Another text';
$resultBool = isset($array['boolValue']) ?? true;
But the point of ??
但是重点呢
??
is that it does the isset
call for you. 是它为您执行了
isset
调用。 So try this, just put the values without using isset
: 因此,请尝试此操作,而无需使用
isset
即可放置值:
$resultInt = $array['intValue'] ?? -1;
$resultString = $array['stringValue'] ?? 'Another text';
$resultBool = $array['boolValue'] ?? true;
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