Example of PHP numerical verification code_PHP tutorial

It is very convenient to implement verification code in php. The key point is to master the usage of php gd library and session.

Looking at the examples of PHP generating verification codes on the Internet, it is all done by combining the PHP gd library with the session and using PHP to generate random numbers.

PHP verification code can be divided into many types, including php picture verification code, php random verification code, and php Chinese verification code, etc. Different verification codes are used according to different application scenarios.

Here is a PHP digital verification code for your reference.

1. Digital verification code

Please enter the verification code: "width:80px">

"Verification"value="Submit verification code">

echo$authnum;?>>

echo$authnum;?>>

2. authimg.php

2. //Generate verification code image
3. Header("Content-type:image/PNG");
4. srand((double)microtime()*1000000);//Sow a seed to generate random numbers to facilitate the use of random number generation below
6. session_start();//Save random numbers into session
7. $_SESSION['authnum']="";
8. $im=imagecreate(62,20);//Specify the image background size
10. $black=ImageColorAllocate($im,0,0,0);// Set three colors
11. $white=ImageColorAllocate($im,255,255,255);
12. $gray=ImageColorAllocate($im,200,200,200);
14. imagefill($im,0,0,$gray);//Adopt area Filling method, set (0,0)
16. while(($authnum=rand()%100000)<10000);
17. //Draw the four-digit integer verification code into the picture
18. // www.jbxue.com
19. $_SESSION['authnum']=$authnum;
20. imagestring($im,5,10,3,$authnum,$black);
21. //Use col color to draw the string s to the x, y coordinates of the image represented by image (the upper left corner of the image is 0,0).
22. //If font is 1, 2, 3, 4 or 5, use the built-in font
24. for($i=0;$i< 200;$i++)//Add interference pixels
25. {
26. $randcolor=ImageColorallocate($im,rand(0,255),rand(0,255),rand(0,255)) ;
27. imagesetpixel($im,rand()%70,rand()%30,$randcolor);
28. }
29. ImagePNG($im);
30. ImageDestroy($im);
31. ?>

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