How to convert string to picture? it's actually really easy! ! !

How to convert string to picture? it's actually really easy! ! !
Copy Verify.class.php to Mobile.class.php
Modify 164 behavior
$code[$i] = $this->codeSet[$i];$config = array('length' => 11);<br>         $Verify = new ThinkMobile($config);<br> ​​​​//Set the verification code characters to pure numbers<br>          $Verify -> codeSet = '13999999999';<br> $Verify -> entry();