how to create captcha code in php???

Answer 1

1. create random string and save this with session in db
2. check user input with saved string in db

Answer 2

trying creating different array variables to hold characters you want to hold display. each array representing one character in the captcha.
Then use the shuffle function on each array and a rand() to randomly pick an index from the range of your arrays and then echo with concatenation.
it's really brute forcing it, but it should work for a basic captcha.

Answer 3

You can learn how to create Captcha code in PHP http://www.phpcluster.com/create-captcha-code-php/