Question

我正在使用http://php.net/manual/en/migration70.new-features.php描述的PHP的空合并操作符。

Null coalescing operator ¶
The null coalescing operator (??) has been added as syntactic sugar for the common case of needing to use a ternary in conjunction with isset(). It returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

<?php
// Fetches the value of $_GET['user'] and returns 'nobody'
// if it does not exist.
$username = $_GET['user'] ?? 'nobody';
// This is equivalent to:
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

// Coalescing can be chained: this will return the first
// defined value out of $_GET['user'], $_POST['user'], and
// 'nobody'.
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';
?>

我注意到以下内容并没有产生预期的结果，那就是要向phone添加一个新的$params索引，其值为“ default”。

$params=['address'=>'123 main street'];
$params['phone']??'default';

为什么不呢？

Answer 1

您不添加任何参数。您给定的代码只是生成未使用的返回值：

$params['phone'] ?? 'default'; // returns phone number or "default", but is unused

因此，您仍然需要设置它：

$params['phone'] = $params['phone'] ?? 'default';

在数组上使用PHP的空合并运算符

1 个答案: