相关疑难解决方法(0)

What is this?

This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list.

Why is this?

It used to be hard to find questions about operators and other syntax tokens.¹
The main idea is to have links to existing questions on Stack Overflow, so it's easier for us to reference them, not to copy over content from …

跨越这行代码:

FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();

这两个问号意味着什么,是某种三元运算符？谷歌很难找到.

许多编程语言都有一个coalesce函数(返回第一个非NULL值,例如).遗憾的是,PHP在2009年没有.

在PHP本身获得合并函数之前,用PHP实现一个好方法是什么？

来自C#我必须用PHP做一个项目.

我正在使用此代码:

$transport = 'T';

$vehicle = (
 ( $transport == 'B' ) ? 'bus' :
 ( $transport == 'A' ) ? 'airplane' :
 ( $transport == 'T' ) ? 'train' :
 ( $transport == 'C' ) ? 'car' :
 ( $transport == 'H' ) ? 'horse' :
 'feet' );

echo $vehicle;

我希望它可以打印train,但我明白了horse.键盘示例:http://codepad.org/rWllfrht

谁能解释这种奇怪的行为？