<p>When is it a good idea to use <a href="http://us3.php.net/manual/en/reserved.constants.php" rel="noreferrer"><code>PHP_EOL</code></a>?</p>

<p>I sometimes see this in code samples of PHP. Does this handle DOS/Mac/Unix endline issues?</p>

Yes,
```
PHP_EOL
```
is ostensibly used to find the newline character in a cross-platform-compatible way, so it handles DOS/Unix issues.
Note that
PHP_EOL
represents the endline character for the
current
system. For instance, it will not find a Windows endline when executed on a unix-like system.