影响单行注释的因素有哪些？

Question

I just started to learn the php and found interestingly new only to me that single line php can affect the code (break the code and may output the html):

From the docs:

//  $file_contents  = '<?php die(); ?>' . "
";

Which results in ' . " "; (and whatever is in the lines following it) to be output to the HTML page.

But using comment on this wouldn't affect the code:

$file_contents  = '<' . '?php die(); ?' . '>' . "
";

Ah, its only because of < and > or something else?

So, I'm curious to know what exactly the factors that affect from using single line comment?

Answer 1

This is an excerpt from the php.net website mentioned in my comment:

The "one-line" comment styles only comment to the end of the line or the current block of PHP code, whichever comes first. This means that HTML code after // ... ?> or # ... ?> WILL be printed: ?> breaks out of PHP mode and returns to HTML mode, and // or # cannot influence that. If the asp_tags configuration directive is enabled, it behaves the same with // %> and # %>. However, the tag doesn't break out of PHP mode in a one-line comment.

In your example, it would be the ?> that is breaking out of the comment as new lines and end PHP tags will override comments to end the script, which is why when you split the ? and the > into two strings and concatenated them, it didn't end the comment.