如何確定變量是否是C＃中的類型引用？

Question

StringBuilder first = new StringBuilder(); 
StringBuilder second = first; 

String str = "Love"; 

有沒有辦法檢查變量「second」是否是類型引用，而變量「str」是Type Value？我一直在谷歌搜索仍然無法得到它，在C＃這裏很新。我知道有second.getType()，但是如果第二個是Type Reference，我不知道。

非常感謝。

其他信息

在這裏，我想坦率地說在這裏，我面對的升C編程測試，當然它是一個開放的書測試，因爲我在一個封閉或限制類:-)我不是。我更熟悉PHP，C/C++，Perl，但在C語言中很新，但我喜歡瞭解它。這是他們的測試。我已經填寫了一些功能，只留下了2或3，那些是ref和unref。如果您看到下面的代碼，我需要在PrintSortedData函數中輸出<>之間的引用類型。測試問題在代碼的評論。也許我還沒有正確的編程邏輯。

/// The DataObject class stored with a key 
class DataObject 
{ 
    public string key = ""; 
    public int value = 0; 
    // Populate 
    public DataObject(string k, int v = 0) 
    { 
     key = k; 
     value = v; 
    } 

} 

class Program 
{ 
    static Hashtable Data = new Hashtable(); 
    static string[] StaticData = new string[] { "X-Ray","Echo","Alpha", "Yankee","Bravo", "Charlie", 
     "Delta", "Hotel", "India", "Juliet", "Foxtrot","Sierra", 
     "Mike","Kilo", "Lima", "November", "Oscar", "Papa", "Qubec", 
     "Romeo", "Tango","Golf", "Uniform", "Victor", "Whisky", 
     "Zulu"}; 

    static void Main(string[] args) 
    { 
     for (int i = 0; i < StaticData.Length; i++) 
      Data.Add(StaticData[i].ToLower(), new DataObject(StaticData[i])); 
     while (true) 
     { 
      PrintSortedData(); 
      Console.WriteLine(); 
      Console.Write("> "); 
      string str = Console.ReadLine(); 
      string[] strs = str.Split(' '); 

      if (strs[0] == "q") 
       break; 
      else if (strs[0] == "print") 
       PrintSortedData(); 
      else if (strs[0] == "swap") 
       Swap(strs[1], strs[2]); 
      else if (strs[0] == "ref") 
       Ref(strs[1], strs[2]); 
      else 
       Console.WriteLine("Invalid Input"); 
     } 
    } 

    /// <summary> 
    /// Create a reference from one data object to another. 
    /// </summary> 
    /// <param name="key1">The object to create the reference on</param> 
    /// <param name="key2">The reference object</param> 
    static void Ref(string key1, string key2) 
    { 

    } 

    /// <summary> 
    /// Removes an object reference on the object specified. 
    /// </summary> 
    /// <param name="key">The object to remove the reference from</param> 
    static void UnRef(string key) 
    { 
     // Populate 
    } 



    /// <summary> 
    /// Prints the information in the Data hashtable to the console. 
    /// Output should be sorted by key 
    /// References should be printed between '<' and '>' 
    /// The output should look like the following : 
    /// 
    /// 
    /// Alpha...... -3 
    /// Bravo...... 2 
    /// Charlie.... <Zulu> 
    /// Delta...... 1 
    /// Echo....... <Alpha> 
    /// --etc--- 
    /// 
    /// </summary> 
    static void PrintSortedData() 
    { 
     // Populate 
     ArrayList keys = new ArrayList(Data.Keys); 
     keys.Sort(); 

     foreach (object obj in keys) 
     { 
      Console.Write(obj + "......." + ((DataObject)Data[obj]).value + "\n"); 
     } 
    } 
} 

Answer 1

first和second是StringBuilder類型的兩個引用。它們碰巧是對同一個對象的引用;換句話說，它們具有相同的對象標識。 str是類型String的參考。

Answer 2

這兩個變量都是引用類型。對象StringBuilder的一個實例仍然是引用類型，因爲是string類型的對象。在C＃

值類型或者是用戶定義structs，枚舉和數值類型（如int，float，double，decimal等）參見Value Types的文檔的詳細信息。

引用類型是其他所有內容，包括類，接口，委託，甚至一些內置類型，如string和object。有關令人驚訝的更多細節，請參見Reference Types上的文檔。至於你的隱含問題，你如何確定一個變量，持有你直接實例化的對象和一個變量，持有隱式引用該對象，你不能。在C＃中，這些都是一樣的。這兩個變量都不包含該對象，而是指向該對象的指針（即對該對象位置的間接引用）。

當然，不要擔心沒有辦法區分二者，因爲它們具有完全相同的功能。如果修改任何一個指向的對象，還可以修改另一個指向的對象。

Answer 3

在這裏我想坦率地說，我正面臨C Sharp的編程測試。我更熟悉PHP，C/C++，Perl，但在C語言中很新，但我喜歡瞭解它。這是他們的測試。我已經填寫過的一些功能，只剩下了2或3，這些都是

/// The DataObject class stored with a key 
class DataObject 
{ 
    public string key = ""; 
    public int value = 0; 
    // Populate 
    public DataObject(string k, int v = 0) 
    { 
     key = k; 
     value = v; 
    } 

} 

class Program 
{ 
    static Hashtable Data = new Hashtable(); 
    static string[] StaticData = new string[] { "X-Ray","Echo","Alpha", "Yankee","Bravo", "Charlie", 
     "Delta", "Hotel", "India", "Juliet", "Foxtrot","Sierra", 
     "Mike","Kilo", "Lima", "November", "Oscar", "Papa", "Qubec", 
     "Romeo", "Tango","Golf", "Uniform", "Victor", "Whisky", 
     "Zulu"}; 

    static void Main(string[] args) 
    { 
     for (int i = 0; i < StaticData.Length; i++) 
      Data.Add(StaticData[i].ToLower(), new DataObject(StaticData[i])); 
     while (true) 
     { 
      PrintSortedData(); 
      Console.WriteLine(); 
      Console.Write("> "); 
      string str = Console.ReadLine(); 
      string[] strs = str.Split(' '); 

      if (strs[0] == "q") 
       break; 
      else if (strs[0] == "print") 
       PrintSortedData(); 
      else if (strs[0] == "swap") 
       Swap(strs[1], strs[2]); 
      else if (strs[0] == "ref") 
       Ref(strs[1], strs[2]); 
      else 
       Console.WriteLine("Invalid Input"); 
     } 
    } 

    /// <summary> 
    /// Create a reference from one data object to another. 
    /// </summary> 
    /// <param name="key1">The object to create the reference on</param> 
    /// <param name="key2">The reference object</param> 
    static void Ref(string key1, string key2) 
    { 

    } 

    /// <summary> 
    /// Removes an object reference on the object specified. 
    /// </summary> 
    /// <param name="key">The object to remove the reference from</param> 
    static void UnRef(string key) 
    { 
     // Populate 
    } 



    /// <summary> 
    /// Prints the information in the Data hashtable to the console. 
    /// Output should be sorted by key 
    /// References should be printed between '<' and '>' 
    /// The output should look like the following : 
    /// 
    /// 
    /// Alpha...... -3 
    /// Bravo...... 2 
    /// Charlie.... <Zulu> 
    /// Delta...... 1 
    /// Echo....... <Alpha> 
    /// --etc--- 
    /// 
    /// </summary> 
    static void PrintSortedData() 
    { 
     // Populate 
     ArrayList keys = new ArrayList(Data.Keys); 
     keys.Sort(); 

     foreach (object obj in keys) 
     { 
      Console.Write(obj + "......." + ((DataObject)Data[obj]).value + "\n"); 
     } 
    } 
}