Since most hosters don't provide access to Apache error logs on shared hosting packages for technical reasons, you can create your own error logs for debugging PHP Scripts. (See the demo at http://programmabilities.com/error_log.php.)

Insert the following code in your PHP script. (Or create separate file and add the code in it. Include the file using include().)

/* we will do our own error handling. */
error_reporting(0); // Turns off all error reporting.

/* user defined error handling function. */
function userErrorHandler($errno, $errmsg, $filename, $linenum, $vars) 
{
    // timestamp for the error entry.
    $dt = date('Y-m-d H:i:s (T)');

    // define an assoc array of error string
    // in reality the only entries we should
    // consider are E_WARNING, E_NOTICE, E_USER_ERROR,
    // E_USER_WARNING and E_USER_NOTICE.
    $errortype = array (
                E_ERROR => 'Error',
                E_WARNING => 'Warning',
                E_PARSE => 'Parsing Error',
                E_NOTICE => 'Notice',
                E_CORE_ERROR => 'Core Error',
                E_CORE_WARNING => 'Core Warning',
                E_COMPILE_ERROR => 'Compile Error',
                E_COMPILE_WARNING => 'Compile Warning',
                E_USER_ERROR => 'User Error',
                E_USER_WARNING => 'User Warning',
                E_USER_NOTICE => 'User Notice',
                E_STRICT => 'Runtime Notice'
                );
    // set of errors for which a var trace will be saved.
    $user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);
  
    $err = "<errorentry>\n";
    $err .= "\t<datetime>" .$dt. "</datetime>\n";
    $err .= "\t<errornum>" .$errno. "</errornum>\n";
    $err .= "\t<errortype>" .$errortype[$errno]. "</errortype>\n";
    $err .= "\t<errormsg>" .$errmsg. "</errormsg>\n";
    $err .= "\t<scriptname>" .$filename. "</scriptname>\n";
    $err .= "\t<scriptlinenum>" .$linenum. "</scriptlinenum>\n";

    if (in_array($errno, $user_errors)) {
        $err .= "\t<vartrace>" .wddx_serialize_value($vars, 'Variables'). "</vartrace>\n";
    }
    $err .= "</errorentry>\n\n";

    // save to the error log file, and e-mail me if there is a critical user error.
    error_log($err, 3, '../error_log.log');
    if ($errno == E_USER_ERROR) {
        mail('bgates@gmail.com', 'Critical User Error', $err);
    }
}
$old_error_handler = set_error_handler('userErrorHandler');