簡單購物車

using System;
using System.Data;
using System.Configuration;
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.Data.SqlClient;

/// <summary>
/// Cart 的摘要說明
/// </summary>
public class Cart
{
 public Cart()
 {
  //
  // TODO: 在此處添加構造函數邏輯
  //
 }

    public void addItem(string name, int quantity, decimal price)
    {
        if (System.Web.HttpContext.Current.Session["Cart"] == null)
        {
            DataTable newdt = new DataTable();
            newdt.Columns.Add("ID", typeof(int));
            newdt.Columns["ID"].AutoIncrement = true;
            newdt.Columns["ID"].AutoIncrementSeed = 1;
            newdt.Columns.Add("ProductName", typeof(string));
            newdt.Columns.Add("Quantity", typeof(int));
            newdt.Columns.Add("Price", typeof(decimal));
            //newdt.Columns.Add("UersName", typeof(string));
            newdt.Columns.Add("Total", typeof(decimal));//hgh
            newdt.PrimaryKey = new DataColumn[] { newdt.Columns[0] };

            DataRow dr = newdt.NewRow();
            dr["ProductName"] = name;
            dr["Quantity"] = quantity;
            dr["Price"] = price;
            //dr["UersName"] = username;
            dr["Total"] = price * quantity;//jkj
            newdt.Rows.Add(dr);
            System.Web.HttpContext.Current.Session["Cart"] = newdt;
        }
        else
        {
            DataTable dt = (DataTable)System.Web.HttpContext.Current.Session["Cart"];
            bool match = false;
            foreach (DataRow dr in dt.Rows)
            {
                if (dr["ProductName"].ToString() == name)
                {
                    int num = Convert.ToInt32(dr["Quantity"]);
                    num += 1;
                    dr["Quantity"] = num;
                    match = true;
                }
            }
            if (!match)
            {
                DataRow dr = dt.NewRow();
                dr["ProductName"] = name;
                dr["Quantity"] = quantity;
                dr["Price"] = price;
                //dr["UersName"] = username;
                dr["Total"] = price * quantity;//jkj
                dt.Rows.Add(dr);
                System.Web.HttpContext.Current.Session["Cart"] = dt;
            }
        }
    }
    public void delete(int id)
    {
        DataTable dt = (DataTable)System.Web.HttpContext.Current.Session["Cart"];
        dt.Rows.Find(id).Delete();
        System.Web.HttpContext.Current.Session["Cart"] = dt;
    }
    public decimal Total()
    {
        DataTable dt = (DataTable)System.Web.HttpContext.Current.Session["Cart"];
        DataRow dr;
        int counter;
        decimal total = 0;
        for (counter = 0; counter < dt.Rows.Count; counter++)
        {
            dr = dt.Rows[counter];
            total += decimal.Parse(dr["Price"].ToString()) * Int32.Parse(dr["Quantity"].ToString());
        }
        return total;
    }
    public void update(int id, int updateNum)
    {
        DataTable dt = (DataTable)System.Web.HttpContext.Current.Session["Cart"];
        DataRow dr = dt.Rows.Find(id);
        dr["Quantity"] = updateNum;
        dr["Total"] =Convert.ToDecimal(dr["Price"])*updateNum;//jkj
        System.Web.HttpContext.Current.Session["Cart"] = dt;
    }

}