PHP验证码生成程序几种方法

$arr=array(2,3,4,5,8,1,9,7,"a","b","c","d","e","f","中","国","南","北","大","小","多","少");
$b=array_rand($arr,3);

?>
<form action="yz.php" method="post">
<input type="text" name="code" />
<input type="hidden" name="yanzhengma" value="<?php foreach($b  as $key)
         {
          echo $arr[$key];
         }
       ?>"
/>

<input type="submit" name="submit" value="do" />
</form>
<?php

echo “code:";
foreach($b  as $key)
{
 echo $arr[$key];
}
?>

</body>
</html>（以上语句另存为一个php文件）

<?php
header(“Content-Type:text/html;charset=utf-8");
echo $_POST["yanzhengma"];
echo $_POST["code"];
if($_POST["yanzhengma"]==$_POST["code"])
{
 echo “验证码正确";
}
else
{
 die(“<script>alert(‘验证码不正确");location="array_rand.php";</script>");
}
?>

UPCAbarcode('12345678901');

?>

$im = imagecreate(60,30);//定义图片宽度和高度
$vcode=getVCode();//获取要显示的字符
$bg = imagecolorallocate($im, 255, 255, 255);//定义图片背景
$txt = imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));//定义要显示字符的颜色
imagestring($im, 8, 0, 0, $vcode, $txt);//写入字符串到图片
header(Content-type: image/jpeg);//定义Content-type
imagejpeg($im);//以JPEG格式显示图片
$_SESSION[vcode]=$vcode;//写入SESSION
 
function getVCode(){    //随机生成用户指定个数的字符串
  $codenum=4;
  $checkcode="";
  $string="";//要显示的可选字符串，请自行定义；
  for($i=0;$i<$codenum;$i  ) {  
  $number=rand(0,2);  
  switch($number){  //根据可选字符串可灵活定义；
       case 0 : $rand_number=rand(0,10);break;   
       case 1 : $rand_number=rand(11,36);break;  
       case 2 : $rand_number=rand(37,62);break;  
  }  
  $code=substr($string,$rand_number,1);
  $checkcode=$checkcode.$code;  
  } 
  return  $checkcode;
}     
?>

function getVCode() {
        var vcode=document.getElementById('vcode');
        vcode.src = 'vcode.php?nocache='+new Date().getTime();
}

//该函数用来验证验证码
function usrVCode() {
        if(!checkLogin())return false;
        var loginvcode=document.loginform.loginvcode.value;
        var xmlhttp1=createAjax();
        var data='&loginvcode='+loginvcode;
if (xmlhttp1) {
  var state=document.getElementById('state');
          xmlhttp1.open('get',?do=vcodedo'+data,true);
  xmlhttp1.send(null);
  xmlhttp1.onreadystatechange=function() {
    if (xmlhttp1.readyState==4 && xmlhttp1.status==200) {
             setTimeout("state.style.display = 'none';",1000);
     var myres=xmlhttp1.responseText;
             var result=(myres==1)?"恭喜您,验证码输入正确!":"很抱歉,验证码输入错误!";
             if(myres==0)alert(result);
             if(myres==1)usrLogin();
            }
    else {
             state.style.display = "";
     state.style.left=(document.body.offsetWidth-350)/2;
             state.style.top=(document.body.offsetHeight-235)/2+document.body.scrollTop;
    }
          }
}
}