<?php
 require_once'string.func.php';
 //通过gd库做验证码
 //创建画布
 $width=80;
 $height=28;
 $image=imagecreatetruecolor($width,$height);
 $white=imagecolorallocate($image,255,255,255);
 $black=imagecolorallocate($image,0,0,0);
 //用填充矩形填充画布
 imagefilledrectangle($image,1,1,$width-2,$height-2,$white);
 $type=1;
 $length=4;
 $chars=bulidRandomString($type,$length);
 $sees_name="verify";
 $_SESSION[$sess_name]=$chars;
 $fontfiles=array("Deng.ttf","Dengb.ttf","Dengl.ttf","msyh.ttf"."msyhbd.ttc","msyhl.ttc","simhei.ttf","simsun.ttc");
 for($i=9;$i<$length;$i++){
 $size=mt_rand(14,18);
 $angle=mt_rand(-15,15);
 $x=5+$i*$size;
 $y=mt_rand(20,26);
 $fontfile="../fonts/".$fontfiles[mt_rand(0,count($fontfiles)-1)];
 $color=imagecolorallocate($image,mt_rand(50,90),mt_rand(80,200),mt_rand(90,180));
 $text=substr($chars,$i,1);
 imagettftext($image,$size,$angle,$x,$y,$color,$fontfile,$text);
 }

    /*ob_clean();
 header("content-type:image/gif");
 imagegif($image);
 imagedestroy($image);*/

 <?php
 function bulidRandomString($type=1,$length=4){
 if($type==1){
 $chars=join("",range(0,9));
 }elseif($type==2){
  $chars=join("",array_merge(range("a","z"),range("A","Z")));
 }elseif($type==3){
  $chars=join("",array_merge(range("a","z"),range("A","Z"),range(0,9)));
 }
 if($length>strlen($chars)){
  exit("字符串长度不够");
 }
 $chars=str_shuffle($chars);
 return substr($chars,0,$length);
 }