找不到命名空間，但已創建？

Question

我正在研究一個基本完成的程序。但唯一的問題是我無法通過這個錯誤。

錯誤1：類型或命名空間名稱「項目」找不到（是否缺少using指令或程序集引用？）

有人能向我解釋爲什麼我收到這個名稱確實有參考時出錯？ （據我所知）。

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Data.SqlClient; 
using System.Data; 
using System.Data.Odbc; 
using System.IO; 
using System.Xml; 
using System.Net; 



namespace Lab_5 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 

      string conString = "Driver={MySQL ODBC 5.3 ANSI Driver};" 
       + "Server=xxx;Port=xxx;" 
       + "Database=xxx;" 
       + "uid=xxx;pwd=xxx"; 
      OdbcConnection connection = new OdbcConnection(conString); 
      connection.Open(); 




      string filepath = @"f:\sai430\output\"; 
      string filename = @"Update.xml"; 


      XmlReader theFile = XmlReader.Create(filepath + filename); 




      while (theFile.Read()) 
      { 
        Item theItem = new Item(); 
       Item theItem = new Item(); 



       if (theFile.Name.Equals("ADD")) 
       { 
        if (theFile.Name.Equals("ADD")) 
         Console.WriteLine("Item " + theItem.Item_ID + " was added successfully."); 
        else 
         Console.WriteLine("Problem upadating " + theItem.Item_ID + "."); 

       } 

       else if (theFile.Name.Equals("UPDATE")) 
       { 
        if (theFile.Name.Equals("UPDATE")) 
         Console.WriteLine("Item " + theItem.Item_ID + " was updated successfully."); 
        else 
         Console.WriteLine("Problem upadating " + theItem.Item_ID + "."); 
       } 

       else if (theFile.Name.Equals("DELETE")) 
       { 
        if (theFile.Name.Equals("DELETE")) 
         Console.WriteLine("Item " + theItem.Item_ID + " was deleted successfully."); 
        else 
         Console.WriteLine("Problem deleting " + theItem.Item_ID + "."); 

      } 



     } 

這是我有我的Class.cs

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Data; 
using System.Data.SqlClient; 
using System.Data.Odbc; 
using System.IO; 
using System.Configuration; 
using System.Xml; 



namespace ProjectLab4 
{ 
    class LClass5 
    { 

     public int Item_ID { get; set; } 
     public int Invent_id { get; set; } 
     public string Itemsize { get; set; } 
     public string Color { get; set; } 
     public decimal Curr_price { get; set; } 
     public int Qoh { get; set; } 


     public bool ParseCSVline(string aLine) 
     { 
      try 
      { 
       string[] fields = aLine.Split(','); 
       this.Item_ID = int.Parse(fields[0]); 
       this.Invent_id = int.Parse(fields[1]); 
       this.Itemsize = fields[2]; 
       this.Color = fields[3]; 
       this.Curr_price = decimal.Parse(fields[4]); 
       this.Qoh = int.Parse(fields[5]); 
       return true; 
      } 
      catch (Exception ex) 
      { 
       return false; 
      } 
     } 


     public bool IsInDatabase(OdbcConnection db) 
     { 
      String sql = "SELECT * FROM item WHERE item_ID=?"; 
      OdbcCommand Command = new OdbcCommand(sql, db); 

      Command.Parameters.Add("@ID", OdbcType.Int).Value = this.Item_ID; 


      if (Command.ExecuteReader().HasRows) 
       return true; 
      else 
       return false; 
     } 


     public bool AddRow(OdbcConnection db) 
     { 
      String sql = "INSERT INTO item " 
         + "(item_id, invent_id, itemsize, color, curr_price, qoh) " 
         + "VALUES(?, ?, ?, ?, ?, ?)"; 
      OdbcCommand Command = new OdbcCommand(sql, db); 
      Command.Parameters.Add("@ID", OdbcType.Int).Value = this.Item_ID; 
      Command.Parameters.Add("@INVID", OdbcType.Int).Value = this.Invent_id; 
      Command.Parameters.Add("@SZ", OdbcType.VarChar).Value = this.Itemsize.Trim(); 
      Command.Parameters.Add("@COL", OdbcType.VarChar).Value = this.Color.Trim(); 
      Command.Parameters.Add("@PR", OdbcType.Double).Value = (double)this.Curr_price; 
      Command.Parameters.Add("@QOH", OdbcType.Int).Value = this.Qoh; 

      int result = Command.ExecuteNonQuery(); //Returns 1 if successful 
      if (result > 0) 
       return true; //Was successful in adding 
      else 
       return false; //failed to add 
     } 

     public bool UpdateRow(OdbcConnection db) 
     { 
      String sql = "UPDATE item " 
       + "SET itemsize=?, " 
       + "color=?, " 
       + "curr_price=?, " 
       + "qoh=? " 
       + "WHERE item_id=?"; 
      OdbcCommand Command = new OdbcCommand(sql, db); 
      Command.Parameters.Add("@SZ", OdbcType.VarChar).Value = this.Itemsize.Trim(); 
      Command.Parameters.Add("@COL", OdbcType.VarChar).Value = this.Color.Trim(); 
      Command.Parameters.Add("@PR", OdbcType.Double).Value = (double)this.Curr_price; 
      Command.Parameters.Add("@QOH", OdbcType.Int).Value = this.Qoh; 
      Command.Parameters.Add("@ID", OdbcType.Int).Value = this.Item_ID; 
      int result = Command.ExecuteNonQuery(); //Returns 1 if successful 
      if (result > 0) 
       return true; //Was successful in updating 
      else 
       return false; //failed to update 
     } 

     public bool DeleteRow(OdbcConnection db) 
     { 
      String sql = "DELETE FROM item WHERE item_id=?"; 
      OdbcCommand Command = new OdbcCommand(sql, db); 
      Command.Parameters.Add("@ID", OdbcType.Int).Value = this.Item_ID; 
      int result = Command.ExecuteNonQuery(); //Returns 1 if successful 
      if (result > 0) 
       return true; //Was successful in deleting 
      else 
       return false; //failed to delete 
     } 

     public bool parseXML(XmlReader f) 
     { 
      try 
      { 
       this.Item_ID = int.Parse(f.GetAttribute("item_id")); 
       this.Invent_id = int.Parse(f.GetAttribute("invent_id")); 
       this.Itemsize = f.GetAttribute("itemsize"); 
       this.Color = f.GetAttribute("color"); 
       this.Curr_price = decimal.Parse(f.GetAttribute("curr_price")); 
       this.Qoh = int.Parse(f.GetAttribute("qoh")); 
      } 
      catch (Exception ex) 
      { 
       return false; 
      } 
      return true; 
     } 
     //Get this item from the XML file and 
     //add this item to the database passed in as db 
     public bool XMLAdd(XmlReader f, OdbcConnection db) 
     { 
      if (!this.parseXML(f)) //parse the item from "f" 
       return false; //Leave if the parse failed 


      //Is it in database? Check that it is NOT. 
      if (!this.IsInDatabase(db)) 
      { 
       //if not, add it 
       if (this.AddRow(db)) 
        return true; 
       else 
        return false; //if something went wrong 
      } 
      else 
       return false; //already in DB 
     } 
     //Get this item from the XML file and 
     //add this item to the database passed in as db 
     public bool XMLUpdate(XmlReader f, OdbcConnection db) 
     { 
      if (!this.parseXML(f)) //parse the item from "f" 
       return false; //Leave if the parse failed 


      //Is it in database? Check that it is NOT. 
      if (!this.IsInDatabase(db)) 
      { 
       //if not, update it 
       if (this.UpdateRow(db)) 
        return true; 
       else 
        return false; //if something went wrong 
      } 
      else 
       return false; //already in DB 
     } 
     //Get this item from the XML file and 
     //delete this item from the database passed in as db 
     public bool XMLDelete(XmlReader f, OdbcConnection db) 
     { 
      if (!this.parseXML(f)) //parse the item from "f" 
       this.Item_ID = int.Parse(f.GetAttribute("item_id")); //if the parse fails it will get the items id to delete 

      if (!this.IsInDatabase(db)) 
      { 
       if (this.DeleteRow(db)) 
        return true; 
       else 
        return false; 
      } 
      else 
       return false; 
     } 

Answer 1

綜觀事情，你嘗試在接下來的幾行如

Console.WriteLine("Item " + theItem.Item_ID + " was added successfully."); 

和做事實上，您有一個名爲LClass5的班級，並且該名稱的成員似乎很可能是該行

Item theItem = new Item(); 

應改爲

Item theItem = new LClass5(); 

現在，不會神奇地從你的XML theFile任何信息到theItem，但我看到你有一個LClass5方法parseXML可以幫助你與該步驟。或者也許,XMLUpdate,XMLDelete方法也在LClass5，雖然這些似乎是違反單一責任原則。