支持中文、字母、数字的PHP验证码_php实例

session_start(); getCode(4,60,20);   function getCode($num,$w,$h) {   $code = "";   for ($i = 0; $i < $num; $i++) {     $code .= rand(0, 9);   }   //4位验证码也可以用rand(1000,9999)直接生成   //将生成的验证码写入session，备验证时用   $_SESSION["helloweba_num"] = $code;   //创建图片，定义颜色值   header("Content-type: image/PNG");   $im = imagecreate($w, $h);   $black = imagecolorallocate($im, 0, 0, 0);   $gray = imagecolorallocate($im, 200, 200, 200);   $bgcolor = imagecolorallocate($im, 255, 255, 255);   //填充背景   imagefill($im, 0, 0, $gray);     //画边框   imagerectangle($im, 0, 0, $w-1, $h-1, $black);     //随机绘制<i>1本文来#源gaodai$ma#com搞$代*码*网</i><pre>搞代gaodaima码

两条虚线，起干扰作用 $style = array ($black,$black,$black,$black,$black, $gray,$gray,$gray,$gray,$gray ); imagesetstyle($im, $style); $y1 = rand(0, $h); $y2 = rand(0, $h); $y3 = rand(0, $h); $y4 = rand(0, $h); imageline($im, 0, $y1, $w, $y3, IMG_COLOR_STYLED); imageline($im, 0, $y2, $w, $y4, IMG_COLOR_STYLED); //在画布上随机生成大量黑点，起干扰作用; for ($i = 0; $i < 80; $i++) { imagesetpixel($im, rand(0, $w), rand(0, $h), $black); } //将数字随机显示在画布上,字符的水平间距和位置都按一定波动范围随机生成 $strx = rand(3, 8); for ($i = 0; $i < $num; $i++) { $strpos = rand(1, 6); imagestring($im, 5, $strx, $strpos, substr($code, $i, 1), $black); $strx += rand(8, 12); } imagepng($im);//输出图片 imagedestroy($im);//释放图片所占内存 }