If you just want to suppress warnings, error_reporting(0) might help you. I'm not sure if this needs to be fixed anyhow though...

Doing @highlight_string seems to work to, but it strips the \. Might not fixing, but it still seems like a bug.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

The warning you are seeing is a lexical parser warning, it cannot be avoided simply because it is the same parser as the one parsing normal PHP source. If PHP were to execute the file it too would strip/ignore the \ character.

This bug is not bogus.  We are experiencing it semi-randomly with our pastebin code at http://dalphp.shoggoth.net/pastebin.php (http://dalphp.shoggoth.net/pastebin_view.php?356 is one post being affected)

The code that is paste is generating the warning for \'s which are valid.  In this case, the \ in the \n in the print statements.

Here's some debugging code/output I added to see if this was a bug or not.

-=-=-= code -=-=-=-=-
$src=implode("\n", $Source);
echo '<!-- Source: ', NL, $src, '-->';
if (strpos($src, '<?php') !== false || strpos($src, '<?') !== false){
  $source=highlight_string($src, 1);
  echo '<!-- Source 2: ', NL, $source, ' -->';
  $source=str_replace(array('<code>', '</code>'), '', $source);
}
else {
  $source=nl2br(htmlentities($src));
}
echo $src;
-=-=-=-=-=-=-=-=-=-=-

-=-=-= output -=-=-=-=-
<!-- Source: 
<?php

/* Trying to figure out wtf is thrown when an array is accessed out of bounds. */

print "Before!\n";
    
try {
    print "Trying!\n";
    $x = array(1, 2, 3);
    print_r($x);
    $y = $x[3];
    print_r($y);
}
catch(Exception $e) {
    print "Cought!\n";
    print_r($e);
}

print "Done!\n";

/* Expected output:
 *   Before!
 *   Trying!
 *   Array ( etc.
 *   Cought!
 *   Object ( etc.
 *   Done!
 *
 * Actual output:
 *   Before!
 *   Trying!
 *   Array ( etc.
 *   Done!
 */

?>--><!-- Source 2: 
<code><font color="#000000">
<font color="#0000BB">&lt;?php<br /><br />/* Trying to figure out wtf is thrown when an array is accessed out of bounds. */<br /><br />print </font><font color="#DD0000">"Before!<br />
<b>Warning</b>:  Unexpected character in input:  '\' (ASCII=92) state=1 in <b>/home/trollboy/public_html/dalphp/pastebin_view.php</b> on line <b>153</b><br />
n";<br />&nbsp;&nbsp;&nbsp;&nbsp;<br />try {<br />&nbsp;&nbsp;&nbsp;&nbsp;print "Trying!<br />
<b>Warning</b>:  Unexpected character in input:  '\' (ASCII=92) state=1 in <b>/home/trollboy/public_html/dalphp/pastebin_view.php</b> on line <b>153</b><br />
n"</font><font color="#0000BB">;<br />&nbsp;&nbsp;&nbsp;&nbsp;$x = array(1, 2, 3);<br />&nbsp;&nbsp;&nbsp;&nbsp;print_r($x);<br />&nbsp;&nbsp;&nbsp;&nbsp;$y = $x</font><font color="#007700">[</font><font color="#0000BB">3</font><font color="#007700">]</font><font color="#0000BB">;<br />&nbsp;&nbsp;&nbsp;&nbsp;print_r($y);<br /></font><font color="#007700">}</font><font color="#0000BB"><br />catch(Exception $e) </font><font color="#007700">{</font><font color="#0000BB"><br />&nbsp;&nbsp;&nbsp;&nbsp;print </font><font color="#DD0000">"Cought!<br />
<b>Warning</b>:  Unexpected character in input:  '\' (ASCII=92) state=1 in <b>/home/trollboy/public_html/dalphp/pastebin_view.php</b> on line <b>153</b><br />
n"</font><font color="#0000BB">;<br />&nbsp;&nbsp;&nbsp;&nbsp;print_r($e);<br /></font><font color="#007700">}</font><font color="#0000BB"><br /><br />print </font><font color="#DD0000">"Done!<br />
<b>Warning</b>:  Unexpected character in input:  '\' (ASCII=92) state=1 in <b>/home/trollboy/public_html/dalphp/pastebin_view.php</b> on line <b>153</b><br />
n"</font><font color="#0000BB">;<br /><br />/* Expected output:<br /> *&nbsp;&nbsp;&nbsp;Before!<br /> *&nbsp;&nbsp;&nbsp;Trying!<br /> *&nbsp;&nbsp;&nbsp;Array ( etc.<br /> *&nbsp;&nbsp;&nbsp;Cought!<br /> *&nbsp;&nbsp;&nbsp;Object ( etc.<br /> *&nbsp;&nbsp;&nbsp;Done!<br /> *<br /> * Actual output:<br /> *&nbsp;&nbsp;&nbsp;Before!<br /> *&nbsp;&nbsp;&nbsp;Trying!<br /> *&nbsp;&nbsp;&nbsp;Array ( etc.<br /> *&nbsp;&nbsp;&nbsp;Done!<br /> */<br /><br />?&gt;</font>
</font>
</code> -->
-=-=-=-=-=-=-=-=-=-=-=-


As you can see, the highlight_string call is causing the warning to be injected into the source where they should not be.  The code is fine under normal circumstances.

I am the submitter of Keith's failed post.
The problem only produces itself in Mozilla 1.0 PR.
When I viewed this page in Internet Explorer, the problem was not there.

As proof, I have taken a screenshot:
http://labs.jed.bz/phpbug.png

PHP developers are too quick to mark bugs bogus. Please review this bug's status.

I apologize, an addendum: Mozilla *Firefox* 1.0 PR.

Still seems to be happening, both for me and for others.

This problem still exists in 4.3.9, and I beleive it has been fixed in 5.*. Half the time just shows up blank, so this is a definite bug.

[Correction] This problem still exists in 5.*.

Correct this is a annoying bug because it happens randomly.
My CVS viewer and BB just throw the error occasional without a pattern.

I also found additional problems so maybe someone can trace it.
when you have "<?php" in top sometimes the whole text has blue color and a different time it is in 2 colors (<? = orange, php = blue)
And also the content between <?php and ?> is sometimes colored and sometimes completely blue.

To me this recognizes that the function has trouble with converting the text.

But where does the conversion goes bad in base_functions.c:
zend_parse_parameters(), highlight_string() or even before that ????

Bumping.. This is still an issue.

There is no issue.. simply running:
<?php
$a = 2;
\
$c = 5;
?>

does the same as a php script or running it through highlight_string. stray '\'s outside of a string isn't allowed.