[英]using PHP's null coalescing operator on an array
我正在使用http://php.net/manual/en/migration70.new-features.php描述的 PHP null 合並運算符。
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';
?>
我注意到以下沒有產生我預期的結果, $params
添加一個新的phone
索引,其值為“默認”。
$params=['address'=>'123 main street'];
$params['phone']??'default';
為什么不?
您不添加任何參數。 您的給定代碼只是生成未使用的返回值:
$params['phone'] ?? 'default'; // returns phone number or "default", but is unused
因此,您仍然必須設置它:
$params['phone'] = $params['phone'] ?? 'default';
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.