php简单生成验证码
利用php自身带的函数来实现图片验证码生成功能,php简单生成验证码实例代码如下:
- <?php
- //must start or continue session and save CAPTCHA string in $_SESSION for
- //it to be available to other requests
- if(!isset($_SESSION)){
- session_start();
- header('Cache-control:private');
- }
- //create a 65*20 pixel image
- $width=65;
- $height=20;
- $image=imagecreate(65,20);
- //fill the image background color
- $bg_color=imagecolorallocate($image,0x33,0x66,0xFF);
- imagefilledrectangle($image,0,0,$width,$height,$bg_color);
- //fetch random text
- $text=random_text(5);
- //determine x and y coordinates for centering text
- $font=5;
- $x=imagesx($image)/2-strlen($text)*imagefontwidth($font)/2;
- $y=imagesy($image)/2-imagefontheight($font)/2;
- //write text on image //开源代码phpfensi.com
- $fg_color=imagecolorallocate($image,0xFF,0xFF,0xFF);
- imagestring($image,$font,$x,$y,$text,$fg_color);
- //save the CAPTCHA string for later comparison
- $_SESSION['captcha']=$text;
- //output the image
- header('Content-type:image/png');
- imagepng($image);
- imagedestroy($image);
- ?>