php - Validate input field for max value -

how can verify input field @ maximum 500? possible php-ci controller?

<tr>        <td>price</td>        <td>:</td>        <td><input name="price"type="text"></td> </tr>   

try

<input type="text" maxlength="10"> 

for more details http://www.wufoo.com/html5/attributes/03-maxlength.html