登陆页面验证码　代码

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
using System.Drawing.Imaging;

public partial class Validata : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Session["code"] = RandNum(4);
        ValidateCode(Session["code"].ToString(), 40, 20, "黑体", 10, "#FFFFFF");        
    }

    /// <summary>
    /// 该方法用于生成指定位数的随机数
    /// </summary>
    /// <param name="VcodeNum">参数是随机数的位数</param>
    /// <returns>返回一个随机数字符串</returns>
    private string RandNum(int VcodeNum)
    {
        string Vchar = "0,1,2,3,4,5,6,7,8,9";
        string[] VcArray = Vchar.Split(',');//拆分成数组