PHP NULL Coalescing Operator

PHP 7 New Features

The NULL coalescing operator (??) newly added in PHP 7 is a shortcut for ternary operations that perform isset() checks.

The NULL coalescing operator checks whether a variable exists and is not NULL; if so, it returns its own value, otherwise it returns its second operand.

Previously we wrote the ternary operator like this:

$site = isset($_GET['site']) ? $_GET['site'] : 'Example';

Now we can write it directly like this:

$site = $_GET['site'] ?? 'Example';

Example

<?php
// 获取 $_GET['site'] 的值，如果不存在返回 'Example'
$site = $_GET['site'] ?? 'Example';

print($site);
print(PHP_EOL); // PHP_EOL 为换行符


// 以上代码等价于
$site = isset($_GET['site']) ? $_GET['site'] : 'Example';

print($site);
print(PHP_EOL);
// ?? 链
$site = $_GET['site'] ?? $_POST['site'] ?? 'Example';

print($site);
?>

The output of the above program execution is:

Example
Example
Example

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PHP 7 New Features

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