简单验证码

<?php
session_start();

$im = imagecreatetruecolor(100,50);
$red =imagecolorallocate($im,255,0,0);

$x=rand(0,20);
$y=rand(35,30);
$r=rand(-20,20);
$str[0]='西农';
$str[1]='麦田';
$str[2]='开源';

$n=mt_rand(0,16);
$_SESSION['checkCode']=$str[$n];
imagettftext($im,15,$r,$x,$y,$red,"msyh.ttf",$_SESSION['checkCode']);

header("content-type:image/png");
imagepng($im);
imagedestroy($im);
?>