Complete PHP graphic verification code program source code!

Complete PHP graphic verification code program source code !,

The code is as follows:
/* Website verification code program
* Running environment: PHP5.0.18 is successfully debugged.
* Gd2 graphics library is required (php_gd2.dll is enabled in PHP. INI)
* File name: showimg. php
* Author: 17php.com
* Time: 2007.03
* Technical support: www.17php.com
*/

// Generate a 4-digit verification code randomly
$ Num = "";
For ($ I = 0; $ I <4; $ I ++ ){
$ Num. = rand (0, 9 );
}
// The four-digit verification code can also be directly generated using rand (,)
// Write the generated verification code to the session, which is used on the standby verification page.
Session_start ();
$ _ SESSION ["Checknum"] = $ num;
// Create an image and define the color value
Header ("Content-type: image/PNG ");
Srand (double) microtime () * 1000000 );
$ Im = imagecreate (60, 20 );
$ Black = ImageColorAllocate ($ im, 0, 0 );
$ Gray = ImageColorAllocate ($ im, 200,200,200 );
Imagefill ($ im, 0, 0, $ gray );

// Randomly draw two dotted lines to interfere
$ Style = array ($ black, $ gray, $ gray );
Imagesetstyle ($ im, $ style );
$ Y1 = rand (0, 20 );
$ Y2 = rand (0, 20 );
$ Y3 = rand (0, 20 );
$ Y4 = rand (0, 20 );
Imageline ($ im, 0, $ y1, 60, $ y3, IMG_COLOR_STYLED );
Imageline ($ im, 0, $ y2, 60, $ y4, IMG_COLOR_STYLED );

// Randomly generate a large number of black spots on the canvas, which can interfere with the canvas;
For ($ I = 0; $ I <80; $ I ++)
{
Imagesetpixel ($ im, rand (0, 60), rand (0, 20), $ black );
}
// Display the four numbers randomly on the canvas. the horizontal spacing and position of the characters are randomly generated according to a certain fluctuation range.
$ Strx = rand (3, 8 );
For ($ I = 0; $ I <4; $ I ++ ){
$ Strpos = rand (1, 6 );
Imagestring ($ im, 5, $ strx, $ strpos, substr ($ num, $ I, 1), $ black );
$ Strx + = rand (8, 12 );
}
ImagePNG ($ im );
ImageDestroy ($ im );
?>

Usage:
This program can be run directly. after running the program, you can see a graphic verification code. every time you refresh the code, a new code is randomly generated.
When using this program on a page, you can use the following code:

The code is as follows:
.....
Enter the verification code:


.....

In this way, the verification code image is displayed. On the verification page, use the following code:

The code is as follows:
...
$ Code = $ _ POST ["passcode"];
If ($ code = $ _ SESSION ["Checknum"]) {
Verification passed
} Else {
Incorrect verification code
}
...

Running result