Create a PHP captcha using simple PHP image handling functions. Creating a PHP Captcha image explained. The only difference between a captcha and a normal text written on an image is the former generates random strings and places it crookedly on the image making it difficult for bots to find out. This PHP captcha tutorial will make use of six image functions imagecreate(), imagecolorallocate(), imageline(), imagettftext(), imagepng(), imagedestroy(). You can feel free to modify it and add more functions to bring visual effects. For PHP Random string generation see the previous article.Continue Reading…

Generate a random alphanumeric string containing both uppercase and lowercase characters in PHP. The rand() function in PHP generates a random number we’ll be using this function to generate a random alphanumeric string. A variable should be declared containing all the alphabets in English both uppercase and lowercase (A-Z and a-z) and numbers from 0-9. The concept here is to randomly pick a character from the string containing all the characters and assign it to a variable. Each time this process is done the currently randomly selected character is concatenated with the previously generated characters. This should be done as many times the length of the random string required. For this a looping statement can be used.Continue Reading…