Php entry-level PHP Verification Code Program

To generate a verification code, we need to use php graphics processing functions, such as imagecreate, imagepng, and header. Let's take a look at a simple example.

Instance

The Code is as follows:

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<? Php Session_start (); $ Im = imagecreate (80, 30); // create an image $ Color = imagecolorallocate ($ im, rand (150,200), rand (150,200), rand (150,200); // set the image background $ Str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789"; // generate a random string For ($ I = 0; $ I <5; $ I ++ ){ $ Code. = $ str [rand (0, (strlen ($ str)-1)]; } $ _ SESSION ['code'] = $ code; For ($ a = 0; $ a <5; $ a ++) {// write strings to image resources $ X = $ a * 10 + 15; $ Y = rand (5, 10); // www. bKjia. c0m Imagechar ($ im, 5, $ x, $ y, $ code {$ a}, imagecolorallocate ($ im, 0, 0 )); } Header ("Content-type: image/png"); // outputs image resources Imagepng ($ im ); ?>

Example 2

The Code is as follows:

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<? Php If (! Isset ($ _ SESSION) {// checks whether the session is enabled Session_start (); // enable session } $ Width = 70; // width of the canvas $ Height = 25; // canvas height $ Length = 4; // verification code length $ Code = getcode ($ length); // obtain a random string $ _ SESSION ['verfycode'] = $ code; $ Img = imagecreate ($ width, $ height ); $ Bgcolor = imagecolorallocate ($ img, 240,240,240 ); $ Rectangelcolor = imagecolorallocate ($ img, 150,150,150 ); Imagerectangle ($ img, $ width-1, $ height-1, $ rectangelcolor); // draw a border For ($ I = 0; $ I <$ length; $ I ++) {// circular writing $ Codecolor = imagecolorallocate ($ img, mt_rand (50,200), mt_rand (50,128), mt_rand (50,200 )); $ Angle = rand (-20, 20 ); $ Charx = $ I * 15 + 8; $ Chary = ($ height + 14)/2 + rand (-1, 1 ); Imagettftext ($ img, 15, $ angle, $ charx, $ chary, $ codecolor, 'c: WINDOWSFontsSIMKAI. ttf ', $ Code [$ I]); } For ($ I = 0; $ I <20; $ I ++) {// looping $ Linecolor = imagecolorallocate ($ img, mt_rand (0,250), mt_rand (0,250), mt_rand (0,250 )); $ Linex = mt_rand (1, $ width-1 ); $ Liney = mt_rand (1, $ height-1 ); Imageline ($ img, $ linex, $ liney, $ linex + mt_rand ()-2, $ liney + mt_rand ()-2, $ linecolor ); } For ($ I = 0; $ I <100; $ I ++) {// recurrence point $ Pointcolor = imagecolorallocate ($ img, mt_rand (0,250), mt_rand (0,250), mt_rand (0,250 )); Imagesetpixel ($ img, mt_rand (1, $ width-1), mt_rand (1, $ height-1), $ pointcolor ); } Function getcode ($ length) {// generate a php Random Number $ Pattern = '1234567890abcdefghijklomnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz '; // character pool For ($ I = 0; $ I <$ length; $ I ++ ){ $ Key. = $ pattern {mt_rand (0, 35 )}; } Return $ key; } Ob_clean (); Header ('content-type: image/png '); Imagepng ($ img ); ?>

As follows: