How to Create Captcha in PHP

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In this article, we are going to create Captcha using PHP. This simple article will help you on how to create this simple captcha with this simple source code. Enable you to generate a random code and you can use this to protect your page from random spammers. You can use this also as a type of a simple test that the response is generated by a human being and it's a very common on other websites.

Creating random code, TextBox, and one button as shown in the image below.

Here's the short source code for the image above.

1. <form
   
   class
   
   =
   
   "form-horizontal"
   
   method
   
   =
   
   "POST"
   
   >
   
2. 
   
3. <img
   
   src
   
   =
   
   "generatecaptcha.php?rand=<?php echo rand(); ?>
   
   " id='image_captcha' >
   
4. <a
   
   href
   
   =
   
   'javascript: refreshing_Captcha();'
   
   ><i
   
   class
   
   =
   
   "icon-refresh icon-large"
   
   ></
   
   i
   
   ></
   
   a
   
   >
   
5. <script
   
   language
   
   =
   
   'JavaScript'
   
   type
   
   =
   
   'text/javascript'
   
   >
   
6. function refreshing_Captcha()
   
7. {
   
8. var img = document.images['image_captcha'];
   
9. img.src = img.src.substring(0,img.src.lastIndexOf("?"))+"?rand="+Math.random()*1000;
   
10. }
    
11. </
    
    script
    
    >
    
12. 
    
13. <div
    
    class
    
    =
    
    "control-group"
    
    >
    
14. <label
    
    class
    
    =
    
    "control-label"
    
    for
    
    =
    
    "inputPassword"
    
    >
    
    Enter the Code Above</
    
    label
    
    >
    
15. <div
    
    class
    
    =
    
    "controls"
    
    >
    
16. <input
    
    id
    
    =
    
    "code"
    
    name
    
    =
    
    "code"
    
    type
    
    =
    
    "text"
    
    placeholder=
    
    "Enter the Code Above"
    
    required></
    
    td
    
    >
    
17. </
    
    div
    
    >
    
18. </
    
    div
    
    >
    
19. 
    
20. <div
    
    class
    
    =
    
    "control-group"
    
    >
    
21. <div
    
    class
    
    =
    
    "controls"
    
    >
    
22. <button
    
    type
    
    =
    
    "submit"
    
    name
    
    =
    
    "submit"
    
    class
    
    =
    
    "btn btn-primary"
    
    ><i
    
    class
    
    =
    
    "icon-ok icon-large"
    
    ></
    
    i
    
    >
    
    Submit</
    
    button
    
    >
    
23. </
    
    div
    
    >
    
24. </
    
    div
    
    >
    
25. 
    
26. </
    
    form
    
    >
    

Here's the source code for generating a random code.

1. <
   
   img src=
   
   "generatecaptcha.php?rand=<?php echo rand(); ?>"
   
   id=
   
   'image_captcha'
   
   >
   
2. <
   
   a href=
   
   'javascript: refreshing_Captcha();'
   
   ><
   
   i class
   
   =
   
   "icon-refresh icon-large"
   
   ></
   
   i></
   
   a>
   
3. <
   
   script language=
   
   'JavaScript'
   
   type=
   
   'text/javascript'
   
   >
   
4. function
   
   refreshing_Captcha(
   
   )
   
5. {
   
6. var
   
   img =
   
   document.images
   
   [
   
   'image_captcha'
   
   ]
   
   ;
   
7. img.src
   
   =
   
   img.src
   
   .substring
   
   (
   
   0
   
   ,
   
   img.src
   
   .lastIndexOf
   
   (
   
   "?"
   
   )
   
   )
   
   +
   
   "?rand="
   
   +
   
   Math
   
   .random
   
   (
   
   )
   
   *
   
   1000
   
   ;
   
8. }
   
9. </
   
   script>
   

In the image below, if the user matches random code.

In the image below, if the user does not match the random code.

Hope that this article will help you a lot.

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