爲什麼這個字符串總是回覆爲「」？

Question

繼承人我的代碼：

public userScreen(string uName) 
    { 
     InitializeComponent(); 
     userName = uName; 
     string topLogNumber = "0"; 
     textBox2.Text = userName; 
     Conversion(topLogNumber); 
     textBox1.Text = topLogNumber; 
     this.WindowState = FormWindowState.Maximized; 

private string Conversion(string lognumber) 
    { 
     lognumber = gettoplognumber(); 
     int lognumberint = Convert.ToInt32(lognumber); 
     lognumberint = lognumberint+1; 
     lognumber = lognumberint.ToString(); 
     return lognumber; 
    } 

private string gettoplognumber() 
    { 
     string selectTopLogNumber = "SELECT MAX (LogNo) from Logs"; 
     string connection = "Data Source = \"EventControl.sdf\""; 
     SqlCeConnection connexion = new SqlCeConnection(connection); 
     SqlCeCommand topLog = new SqlCeCommand(selectTopLogNumber, connexion); 
     try 
     { 
      connexion.Open(); 
     } 
     catch (Exception ex) 
     { 
      MessageBox.Show(ex.ToString()); 
      return "error"; 
     } 
     return topLog.ExecuteScalar() as string; 

現在，這個代碼是尋找到一個數據庫中，由一個遞增的數量。當它運行時（我調試了整個過程），出於某種原因，它一切正常，直到它達到textBox1.Text = topLogNumber;此時它會變回「」。任何人？？？？

Answer 1

更改此行得到轉換的結果

topLogNumber = Conversion(topLogNumber); 

或只是轉換的結果分配給您的文本框

textBox1.Text = Conversion(topLogNumber); 

計算裏面Conversion在返回傳回的結果聲明。您需要將該calc的結果重新分配到userScreen內使用的變量topLogNumber。