php - "elseif"和 "else if"完全是同义词吗？

Question

elseif 和 else if 完全是同义词，还是有区别？

Zend 有公认的“标准”吗？

虽然我个人不喜欢在代码中看到 elseif，但我只需要知道它们是否是同义词，而且 PHP 手册不是最容易搜索的。

Answer 1

来自PHP manual :

In PHP, you can also write 'else if' (in two words) and the behavior would be identical to the one of 'elseif' (in a single word). The syntactic meaning is slightly different (if you're familiar with C, this is the same behavior) but the bottom line is that both would result in exactly the same behavior.

本质上，它们的行为是相同的，但 else if 在技术上等同于这样的嵌套结构:

if (first_condition)
{

}
else
{
  if (second_condition)
  {

  }
}

手册还注明:

Note that elseif and else if will only be considered exactly the same when using curly brackets as in the above example. When using a colon to define your if/elseif conditions, you must not separate else if into two words, or PHP will fail with a parse error.

这意味着在正常的控制结构形式中(即使用大括号):

if (first_condition)
{

}
elseif (second_condition)
{

}

可以使用 elseif 或 else if。但是，如果您使用 alternate syntax , 你必须使用 elseif:

if (first_condition):
  // ...
elseif (second_condition):
  // ...
endif;