How to modify the digital verification code displayed in dedecms

Dedecms shows the modification method of the digital verification code. it is annoying to enter the letter verification code, especially uppercase letters. Then find the file and modify it to a digital verification code.
Modify the file verification code file location
Include \ validateimg. php
Find
For ($ I = 0; $ I <4; $ I ++)
{
$ Rndstring. = chr (mt_rand (65,90 ));
}
Change
For ($ I = 0; $ I <4; $ I ++)
{
$ Rndstring. = chr (mt_rand (48, 57 ));
}
This function generates random characters. if you see no number in it, it is the range of the character and keyboard code to be generated.
Mt_rand (), which is the keyboard code from uppercase letters A to Z.
Now, the value is changed to (), which indicates the keyboard code from 0 to 9: mt_rand ).
According to this theory, it is estimated that Chinese characters can be generated.
In this file
$ Bgcolor = ImageColorAllocate ($ im, 248,212, 20 );
$ Black = ImageColorAllocate ($ im, 0, 0 );
Set the background color and text color of the generated image. Three numbers indicate the values of red, green, and blue. The value range is 0 to 255,
For example
0, 0, 0 indicates black,
255, 0, 0 indicates pure red,
0,255, 0 indicates pure green,
0, 0, 255 indicates pure blue.
255.255.255 indicates white.