PHP CAPTCHA Implementation Code Simple example _php tutorial

PHP Verification Code I have said a lot of examples, the following I turn a friend of the good PHP Verification Code program, quite simple friends can refer to.

Recently bored nothing to do, began to do some PHP sharing, the code is relatively simple, but more practical.

This is written four years ago, a few lines of code to implement the four-bit random number of PHP verification code function.

The code is as follows

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Session_Start (); Header ("Content-type:image/jpeg"); $img = Imagecreate (50,20); $white = Imagecolorallocate ($img, 211,213,193); Imagefill ($img, 0,0, $white); for ($i =0; $i <4; $i + +) { $r [$i] = rand (0,9); } $_session[' valid ' = Implode ("", $r); Write to session here to do post-validation for ($i =0; $i <4; $i + +) { if (rand (0,9)%2==0) { Imagechar ($img, 5, ($i + 1) *8,4, $r [$i],imagecolorallocate ($img, Rand (0,150), Rand (0,150), Rand (0,150))); }else{ Imagechar ($img, 5, ($i + 1) *8,2, $r [$i],imagecolorallocate ($img, Rand (0,150), Rand (0,150), Rand (0,150))); } } Imagejpeg ($IMG);

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