Creating a text CAPTCHA in PHP

Creating a text CAPTCHA in PHP involves generating a random string, displaying it with distortion to make it difficult for bots to read, and then verifying the user’s input against the generated string. Below is a basic example of how you can implement this:

For creating CAPTCHA in php first of all we need to create one string with all alphabets (In both case UPPPER and LOWER) and number from 0-9.

<?php
$str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
?>

Now we shuffle this string using str_shuffle() to change position of each character of this $str variable.

<?php
$str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
$shuffle_str=str_shuffle($str);
?>

After that we need to create rendom position for cteate substring form shuffled string. for create rendom position we use rand() function. also for give length to substring function we use strlen() function for get length of total character of string and then substract -6 from length for create substring with length of 6 character.

<?php
$str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
$shuffle_str=str_shuffle($str);
$len=strlen($str)-6;
$position=rand(0,$len);
?>

Now we use substr() function for create substring from shuffle_str and get captch and then print it on website.

<?php
$str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
$shuffle_str=str_shuffle($str);
$len=strlen($str)-6;
$position=rand(0,$len);
$captcha= substr($shuffle_str,$position,6);
echo $captcha;
?>

That’s it, The above given code is full code to Creating a text CAPTCHA in PHP.