Ad block is installed and active. Please support us by disabling it.
HomeSaturday, August 19, 2017, 09:05:09

Creating a CAPTCHA with PHP :: PHP Tutorial

Tuesday, February 10, 15, 14:45:21, 3 Yaers Ago Via wain, Hits: 4778
Captcha Image, This tutorial will show you how to create a form with Captcha.
1.Sessions in PHP are started by using the session_start() function. Like the setcookie( ) function, the session_start( ) function must come before any HTML, including blank lines, on the page.
<?php session_start(); ?>

2.Imagecreatefrompng :: create a new image from file or URL.
$img = imagecreatefrompng('black.png');

3.The function imagecolorallocate creates a color using RGB (red,green,blue) format.
$white = imagecolorallocate($img, 255, 255, 255);

4.Displaying the random text on the captcha image.
$numero = rand(100, 999);

5.Check if the security code and the session value are not blank and if the input text matches the stored text.
if(($_POST['check']) == $_SESSION['check'])
{ echo 'Input OK';
echo 'Input Wrong';



<form method="POST" action="cc.php">
<img src="captchas.php"> <br>
<input type="text" size="10" name="check"> <br>
<input type="submit" name="submit" value="submit">

<?php session_start();
//imagecreatefrompng :: create a new image
//from file or URL
$img = imagecreatefrompng('black.png');
//displaying the random text on the captcha
$numero = rand(100, 999);
$_SESSION['check'] = ($numero);
//The function imagecolorallocate creates a
//color using RGB (red,green,blue) format.
$white = imagecolorallocate($img, 255, 255, 255);
imagestring($img, 10, 8, 3, $numero, $white);
header ("Content-type: image/png"); imagepng($img);

//Sessions in PHP are started by using the
//session_start() function.
//Like the setcookie( ) function,
//the session_start function must come before any HTML,
//including blank lines, on the page.session_start();
//Check if the security code and
//the session value are not blank
//and if the input text matches the stored text
if(($_POST['check']) == $_SESSION['check']) {
echo 'Input OK';
echo 'Input Wrong';

example 2:

Svolte Monday, June 7, 2010, 16:32:25

Thanks a bunch for this script, its really helpful! :)

sivaramakrishnan Monday, July 12, 2010, 06:04:44

Nice,its very useful for me to creating it.

Alif Tuesday, July 27, 2010, 21:05:13

it's nice tutorial, thanks for share the code

Padmashri Friday, August 27, 2010, 06:14:39

Thanks for this php's very helpful for me.

Jeremy Wednesday, September 15, 2010, 09:06:24

thanks for this code ! Just how we can improve the security of this script and generally any captcha script ?

Mihail Tuesday, December 28, 2010, 14:52:12

nice tutorial,
//clear session to prevent re-use


//end of cc.php

jigibau Tuesday, December 28, 2010, 15:50:59

This is a very nice tutorial. Thanks ..

Michael Pedersen Wednesday, December 29, 2010, 10:21:04

Excellent script for beginners like me. I spend sooo much time on other scripts, but this one worked instantly.
Thanks a lot - Michael.

mimija Saturday, January 22, 2011, 05:41:49

Very useful tut, thank you :)

Ronald Paypon Sunday, February 27, 2011, 12:17:10

Simple but wonderful! Thanks a lot for this basic captcha code.

lakshitha Wednesday, March 2, 2011, 13:55:32

i got an issue pls help smone.. i did alert the session variable($_SESSION[\'check\']) in javascript but it alert the prvious captcha. not the current image captcha.(i got this issue whn i need to validate my form on js). here the code snippet

var imageVarification = $(\"#captcha\").val();
var imagecode = ;

lucky Saturday, March 19, 2011, 08:38:31

Thanks a lot!!! this was really helpful

micho Wednesday, May 4, 2011, 06:19:34

Great Tutorial... Thanks for Sharing.

will Tuesday, July 12, 2011, 11:36:02

Thanks for code also. It worked and was very helpful for me.

ronaldo Friday, August 12, 2011, 15:53:49

thanks admin

nero Wednesday, August 31, 2011, 18:14:04

Thanks for share the code

Michael Wednesday, October 12, 2011, 04:53:24

Very useful code, thanks much.

Gane Wednesday, December 28, 2011, 17:07:34

Thanks for this great tutorial, it was really usefull

Matthew Sunday, February 12, 2012, 18:39:24

Really useful bit of code, thanks for that.

blogger Wednesday, April 18, 2012, 11:28:49

Thanks for the very useful article.

Sign In



Creating a CAPTCHA with PHP with imagecreate

This tutorial will show you how to create a form with Captcha, Requirement(s): PHP Server, GD Graphics Library

PHP highlight_string - PHP Tutorial

Outputs or returns a syntax highlighted version of the given PHP code using the colors defined in the built-in syntax highlighter for PHP. Requirement(s): PHP Server.

PHP Redirect

Header (location) redirect must be processed before any output to the browser.

Creating a Math CAPTCHA with PHP - PHP Tutorial

This tutorial will show you how to create a form with Math Captcha.

Filter Words in PHP - PHP Tutorial

Filter bad words in PHP, requirement(s): PHP server

Upload Image with PHP [Example2]

[Example2] Tutorial - How to upload and resize image with PHP

Email Link

HTML email link example

PHP getdate

Returns an associative array containing the date information of the timestamp, or the current local time if no timestamp is given.

How to check checkbox checked

Checking if checkbox is checked with jQuery

Stack Overflow Clone Script - Ja2BU

Open source question and answer script written in PHP, MySQL and jQuery. Main features are: SEO friendly url's, private message system, rating system, comments system.
About Author


Date Registered: Sun, Feb 8, 15
Last Time Online: Thu, Jun 15, 17
So far has created 115 entries.
This author has not yet filled in any details.