PHP 輸入字串轉換 - htmlspecialchars

htmlspecialchars ( string $string [, int $quote_style = ENT_COMPAT [, string $charset [, bool $double_encode = true ]]] )



．'&' (ampersand) becomes '&'
．'"' (double quote) becomes '"' when ENT_NOQUOTES is not set.
．''' (single quote) becomes ''' only when ENT_QUOTES is set.
．'<' (less than) becomes '<'
．'>' (greater than) becomes '>'

資料來源：http://php.net/manual/en/function.htmlspecialchars.php