PHP implements verification code and php Verification Code

PHP implements verification code and php Verification Code

The verification code is implemented using the SESSION function in PHP.
Declare the function session_start () at the top, telling the server that we want to use the function.

session_start(); 

Next we will use the verification code. Here we use the code of an English number as an example.

$ Image = imagecreatetruecolor (100, 30); // create a 100 × 30 canvas $ white = imagecolorallocate ($ image, 255,255,255); // white imagefill ($ image, $ white); // cover the Black canvas

Then, declare an empty variable before the verification code is implemented to store the verification code.

$ Session = ""; // empty variable, containing the verification code for ($ I = 0; $ I <4; $ I ++) {$ size = 6; $ x = $ I * 25 + mt_rand (80,220); $ y = mt_rand (80,220); $ sizi_color = imagecolorallocate ($ image, mt_rand (), mt_rand ), mt_rand (80,220); $ char = join ("", array_merge (range ('A', 'z'), range ('A', 'z '), range (); $ char = str_shuffle ($ char); $ char = substr ($ char,); imagestring ($ image, $ size, $ x, $ y, $ char, $ sizi_color); $ session. = $ char; // assign each value of the verification code to the variable} $ _ SESSION ['session'] = $ session; // the value of this variable is equal to the value entered by the user.

For ($ k = 0; $ k <200; $ k ++) {$ rand_color = imagecolorallocate ($ image, mt_rand (50,200), mt_rand (50,200 ), mt_rand (50,200); imagesetpixel ($ image, mt_rand (), mt_rand (), $ rand_color);} for ($ n = 0; $ n <5; $ n ++) {$ line_color = imagecolorallocate ($ image, mt_rand (80,220), mt_rand (80,220), mt_rand (80,220); imageline ($ image, mt_rand ), mt_rand (), $ line_color);} header ('content-type: image/png '); // set the file output format imagepng ($ image); // output $ image imagedestroy ($ image) in png format; // destroy the image

Use the POST method to receive the verification code. The strtolower function makes the server case insensitive. This effectively reduces the error rate.

If (isset ($ _ POST ['session']) {session_start (); if (strtolower ($ _ POST ['session']) = strtolower ($ _ SESSION ['session']) {echo '<font color = "# 0000CC"> the input is correct </form> ';} else {echo '<font color = "# CC0000"> <B> input error </B> </font>' ;}exit ();}

The following is the HTML page code.

<! DOCTYPE html> 
Here is a special description of the event onclick added to the HTML code. When the user cannot identify the current verification code, he does not need to refresh the browser and directly click "cannot see clearly? Replace the verification code with another one.

The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.