C＃StreamWriter不能隱式地將類型轉換爲字符串到SYSTEMS.IO

Question

我需要使用StreamWriter到寫入/存儲用戶正在輸入的信息。我已經得到了以下代碼的工作。

我現在需要讓它用用戶的名字寫一個文件，並將信息存儲在那裏。

隱藏展開復制代碼

case 2: //enter new user 
    //Enter new user information and add them to file 
    Console.Write("Please Enter the number of users you wish to log: "); 

    iUserNumber = Convert.ToInt32(Console.ReadLine()); 

    //open file for writing, in APPEND mode 
    using (StreamWriter sw = new StreamWriter("NewUser" +sName,".txt", true)) 
    { 
     //loop for each user 
     for (iCount = 1; iCount <= iUserNumber; iCount++) 
     { 
      // enter details 
      Console.Write("Please Enter your Name" + iCount + ": "); 
      sName = Console.ReadLine(); 

      Console.Write("Please Enter the Name of your School: "); 
      sSchoolName = Console.ReadLine(); 
      Console.WriteLine(); 

      Console.Write("Please Enter the Name of your Class: "); 
      sClassName = Console.ReadLine(); 

      // write to file 
      sw.WriteLine(sName); 
      Console.WriteLine(); 
      sw.WriteLine(sSchoolName); 
      Console.WriteLine(); 
      sw.WriteLine(sClassName); 

      Console.WriteLine("User data entered: "); 
     } 
    } 

我似乎無法得到這個工作，並保持未來與這些錯誤：

參數1：無法從「字符串」轉換爲 'System.IO.Stream' FUNCOCO2

未分配的局部變量 'SNAME' FUNCOCO2的錯誤CS0165使用

錯誤CS1503參數2：無法從「字符串」轉換爲 「System.Text.Encoding」

我不知道如何解決這個問題。

我改成了這樣：

case 2: //enter new user 
    //Enter new user information and add them to file 
    Console.Write("Please Enter the number of users you wish to log: "); 
    iUserNumber = Convert.ToInt32(Console.ReadLine()); 
    //enter first name 
    Console.WriteLine("Please enter your first Name: "); 
    sFirstName = Convert.ToString(Console.ReadLine()); 

    //open file for writing, in APPEND mode 
    using (StreamWriter sw = new StreamWriter(sName)) 
    { 
     //loop for each user 
     for (iCount = 1; iCount <= iUserNumber; iCount++) 
     { 
      // enter details 
      Console.Write("Please Enter your Name" + iCount + ": "); 
      sLastName = Console.ReadLine(); 

      Console.Write("Please Enter the Name of your School: "); 
      sSchoolName = Console.ReadLine(); 
      Console.WriteLine(); 

      Console.Write("Please Enter the Name of your Class: "); 
      sClassName = Console.ReadLine(); 

      // write to file 
      sw.WriteLine(sName); 
      Console.WriteLine(); 
      sw.WriteLine(sSchoolName); 
      Console.WriteLine(); 
      sw.WriteLine(sClassName); 

      Console.WriteLine("User data entered: "); 
     } 
    } 

這似乎沒有任何工作。

Answer 1

請按照錯誤消息（如果您雙擊它們指向特定的行號），請閱讀錯誤，然後糾正錯誤。未分配的局部變量 'SNAME' FUNCOCO2

的

---

錯誤CS0165使用你從來沒有定義和分配在流作家用它sName之前。如果您試圖爲每個用戶創建一個文件，那麼您需要更改邏輯以反映該內容，並在循環內而不是在循環外部創建新的Streamwriter。

---

參數1：無法從 '串' 到 'System.IO.Stream' 轉換

new StreamWriter("NewUser" +sName,".txt", true)) 

應該

new StreamWriter("NewUser" +sName + ".txt", true)) 

它不接受一個字符串作爲第一個參數。

---

評論謝謝你，我怎麼會那麼得到的StreamReader來，然後打開該文件？

您需要將循環創建爲流寫入器之外。

//loop for each user 
for (iCount = 1; iCount <= iUserNumber; iCount++) 
{ 
    Console.Write("Please Enter your Name" + iCount + ": "); 
    var sName = Console.ReadLine(); // remove the previous instance you had of sName and make it a scoped variable to the for loop 
    using (StreamWriter sw = new StreamWriter("NewUser" +sName + ".txt", true)) 
    { /*use the streamwriter here */ } 
} 

Answer 2

對於代碼的第一部分，您正嘗試在爲sName分配一個值之前打開一個Streamwriter。 using關鍵字只是確保在代碼退出該部分時正確處理對象，這意味着在這種情況下您不會將文件全部打開。你應該做的是在for循環中打開一個文件。正確的代碼是：

case 2: //enter new user 
      //Enter new user information and add them to file 
      Console.Write("Please Enter the number of users you wish to log: "); 
      iUserNumber = Convert.ToInt32(Console.ReadLine()); 



       //loop for each user 
       for (iCount = 1; iCount <= iUserNumber; iCount++) 
       { 
        // enter details 
        Console.Write("Please Enter your Name" + iCount + ": "); 
        sName = Console.ReadLine(); 

        Console.Write("Please Enter the Name of your School: "); 
        sSchoolName = Console.ReadLine(); 
        Console.WriteLine(); 

        Console.Write("Please Enter the Name of your Class: "); 
        sClassName = Console.ReadLine(); 

        // write to file 
        //open file for writing, in APPEND mode 
        using (StreamWriter sw = new StreamWriter("NewUser" +sName +".txt", true)) 
        { 
         sw.WriteLine(sName); 
         Console.WriteLine(); 
         sw.WriteLine(sSchoolName); 
         Console.WriteLine(); 
         sw.WriteLine(sClassName); 
        } 


        Console.WriteLine("User data entered: "); 

       } 

      } 

編輯：plus，整個'，'而不是'+'在streamwriter的開頭。我錯過了那個顯而易見的贊成。

Answer 3

using (StreamWriter sw = new StreamWriter("NewUser" +sName,".txt", true))

似乎有+ SNAME之後額外的逗號。這逗號應該是一個+以連接3串部分一起

像這樣 using (StreamWriter sw = new StreamWriter("NewUser" + sName + ".txt", true))

Argument 1: cannot convert from 'string' to 'System.IO.Stream' FUNCOCO2 

Error CS0165 Use of unassigned local variable 'sName' FUNCOCO2 

Error CS1503 Argument 2: cannot convert from 'string' to 'System.Text.Encoding' 

錯誤1，因爲「」 NEWUSER「+ SNAME」不是一個有效的文件路徑，因此不能被流

錯誤2，因爲......不知道，因爲我沒有看到你在哪裏聲明SNAME

錯誤3因爲...額外的逗號正在改變你真的想使用構造函數，那多餘的逗號轉彎」。文本」 轉換爲無效的所需編碼。

Answer 4

你可以做這樣的事情：

Console.WriteLine("Please enter your first Name: "); 
      String sFirstName = Console.ReadLine(); 
      String information = String.Empty; 
      String append = String.Empty; 

      while (true) 
      { 

       Console.Write("Please Enter your Name: "); 
       information = information + Console.ReadLine() + " "; 

       Console.Write("Please Enter the Name of your School: "); 
       information = information + Console.ReadLine() + " "; 

       if (information.Trim().Equals("")) 
       { 
        break; 
       } 

       Console.Write("Please Enter the Name of your Class: "); 
       information = information + Console.ReadLine() + "\t"; 

       append = append + information; 
       information = String.Empty; 


      } 

      String fileLocation = "C:...\\New Text Document.txt"; 


      using (StreamWriter sw = new StreamWriter(fileLocation)) 
      { 
       // write to file 
       sw.WriteLine(append); 
       Console.WriteLine("User data entered: "); 

      }