给变量一个默认值的最佳方法(模拟 Perl ||, ||= ) [英] Best way to give a variable a default value (simulate Perl ||, ||= )

问题描述

我喜欢用 Perl 做这种事情:$foo = $bar ||如果 $bar 为空或未定义，则 $baz 将 $baz 分配给 $foo.你还有 $foo ||= $bletch ，它只会将 $bletch 分配给 $foo 如果 $foo未定义或为空.

I love doing this sort of thing in Perl: $foo = $bar || $baz to assign $baz to $foo if $bar is empty or undefined. You also have $foo ||= $bletch which will only assign $bletch to $foo if $foo is not defined or empty.

这种情况下的三元运算符既乏味又令人厌烦.PHP 中肯定有一个简单、优雅的方法吗?

The ternary operator in this situation is tedious and tiresome. Surely there's a simple, elegant method available in PHP?

或者是使用isset()的自定义函数的唯一答案?

Or is the only answer a custom function that uses isset()?

推荐答案

在 PHP 7 中，我们终于有了一种优雅的方法.它被称为空合并运算符.你可以这样使用它:

In PHP 7 we finally have a way to do this elegantly. It is called the Null coalescing operator. You can use it like this:

$name = $_GET['name'] ?? 'john doe';

这相当于

$name = isset($_GET['name']) ? $_GET['name']:'john doe';

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