php中相应的嵌套三元运算符？ [英] corresponding nested ternary operator in php?

问题描述

我想将以下 if if condition 转换为嵌套三元运算符。

I want to convert following if else condition to nested ternary operator.

if ($projectURL) {
    echo $projectURL;
} elseif ($project['project_url']) {
    echo $project['project_url'];
} else {
    echo $project['project_id'];
}

我写的如下。

echo ($projectURL)?$projectURL:($project['project_url'])?$project['project_url']: $project['project_id'];

但是发现它工作不正常。这不是正确的方法吗？

But it is found as not working properly.Is this not a right way?

推荐答案

三元运算符在PHP中是棘手的，因为它们是左关联的（与所有其他语言不同，它是右关联的）。在这种情况下，你需要使用括号来告诉PHP你想要什么：

Ternary operators are tricky thing in PHP, as they are left-associative (unlike all other languages, where it's right-associative). You will need to use parenthesis to tell PHP what you want exactly in this case:

echo ($projectURL ? $projectURL : ($project['project_url'] ? $project['project_url'] : $project['project_id']));

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