ignoring error warnings

I have the following error function:

function myErrorHandler($errno, $errstr, $errfile, $errline)
{
// put your error in file.
$filename = 'error.txt';
global $sql;
$errsql=$sql;
$errorstr = $errno.$errstr.$errfile.$errline."\n\r".$errsql. "\n\r\n\r\n\r";
//echo $errrorstr;
$handle = fopen($filename, 'a');
fwrite($handle, $errorstr);
fclose($handle);
}

How can I get this to not store warnings such as 8Undefined index: HTTP_REFERER ?

undefined index is a E_NOTICE-level error, so setting error-reporting to
error_reporting(E_ALL ^ E_NOTICE);
will prevent it from being reported.

take a look at http://php.net/error-reporting for more details

instead of error_reporting(0); -- I don't want any errors to show but my error handler picks them up and saves them.
i don't want to save any warnings

how do I do this?

Did you even try what GJay suggested? error_reporting(0) is not what he suggested.

For variables that may or may not exist, write code using the isset() function to avoid the generation of the error in the first place, instead of messing around with the error reporting or error handler after the error has already been generated. Your code will actually run faster by doing this as well.

A custom error handler in PHP will get to handle all errors it can - it doesn't use the error_reporting setting to see if it should handle an error or not.