login.asp

这是一个校验验证码

<%
'-------------定义随机码
dim rndnum,verifycode
Randomize
Do While Len(rndnum)<4
num1=CStr(Chr((57-48)*rnd+48))
rndnum=rndnum&num1
loop
session("verifycode")=rndnum
'-------------定义随机码结束
%>
<script language=javascript>
<!--
function admin_login_chk()
{

  var verifycode=document.admin_frm.verifycode.value;

  	if (verifycode=="" || verifycode==null)
{
     alert("对不起！\n\n请输入验证码!");
    return false;
}
   if (document.admin_frm.verifycode.value!=document.admin_frm.verifycode2.value ){
    alert("输入的验证码不正确，请看清后填写！"); 
    document.admin_frm.verifycode.focus();
   return false; 
}
  document.admin_frm.submit();
}

document.admin_frm.password.focus();
-->
</script>
<form name=admin_frm action='loginpro.asp' method=post>

验证码：
<input name=verifycode type=text class=input_val id="verifycode" value='' size=18 maxlength=20 onmouseover=this.focus()>
<%=session("verifycode")%>
<input type="hidden" name="verifycode2" value="<%=session("verifycode")%>">
<img src='image/al_end_right.gif' width="110" height="88" border=0 style="cursor: hand;" onClick="javascript:admin_login_chk();"> </form>