如何爆炸substr - PHP Captcha

Question

I need your help to explode a substr function. It's for a captcha, need to have every character separate, to apply different color on each character.

Thank you.

$authorizedChar= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

$nbChar = rand(4, 8);

$text = substr(str_shuffle($authorizedChar), 0, $nbChar);

Answer 1

Use str_split()

var_dump(str_split('testing'));

Would return:

array (size=7)
  0 => string 't' (length=1)
  1 => string 'e' (length=1)
  2 => string 's' (length=1)
  3 => string 't' (length=1)
  4 => string 'i' (length=1)
  5 => string 'n' (length=1)
  6 => string 'g' (length=1)