ValueType.GetHashCode 方法

public:
 override int GetHashCode();

public override int GetHashCode ();

override this.GetHashCode : unit -> int

Public Overrides Function GetHashCode () As Integer

傳回

Int32

32 位元帶正負號整數，為此執行個體的雜湊碼。A 32-bit signed integer that is the hash code for this instance.

範例

下列範例將示範如何使用 GetHashCode 衍生實值型別來覆寫方法。The following example demonstrates how the GetHashCode method can be overridden by a derived value type.

public ref struct Complex
{
public:
   double m_Re;
   double m_Im;
   virtual bool Equals( Object^ ob ) override
   {
      if ( dynamic_cast<Complex^>(ob) )
      {
         Complex^ c = dynamic_cast<Complex^>(ob);
         return m_Re == c->m_Re && m_Im == c->m_Im;
      }
      else
      {
         return false;
      }
   }

   virtual int GetHashCode() override
   {
      return m_Re.GetHashCode() ^ m_Im.GetHashCode();
   }
};

public struct Complex
{
    public double m_Re;
    public double m_Im;

    public override bool Equals( object ob ){
        if( ob is Complex ) {
            Complex c = (Complex) ob;
            return m_Re==c.m_Re && m_Im==c.m_Im;
        }
        else {
            return false;
        }
    }

    public override int GetHashCode(){
        return m_Re.GetHashCode() ^ m_Im.GetHashCode();
    }
}

Public Structure Complex
   Private m_Re As Double
   Private m_Im As Double
       
   Public Overloads Function Equals(ob As Object) As Boolean
      If TypeOf ob Is Complex Then
         Dim c As Complex = CType(ob, Complex)
         Return m_Re = c.m_Re And m_Im = c.m_Im
      Else
         Return False
      End If
   End Function
   
   
   Public Overloads Function GetHashCode() As Integer
      Return m_Re.GetHashCode() ^ m_Im.GetHashCode()
   End Function

End Structure

備註

GetHashCode方法適用于衍生自的類型 ValueType 。The GetHashCode method applies to types derived from ValueType. 使用衍生類型的一或多個欄位來計算傳回值。One or more fields of the derived type is used to calculate the return value. 如果您呼叫衍生類型的 GetHashCode 方法，則傳回值不太可能適合用來做為雜湊表中的索引鍵。If you call the derived type's GetHashCode method, the return value is not likely to be suitable for use as a key in a hash table. 此外，如果其中一個或多個欄位的值變更，則傳回值可能會不適合用來做為雜湊表中的索引鍵。Additionally, if the value of one or more of those fields changes, the return value might become unsuitable for use as a key in a hash table. 無論是哪一種情況，請考慮撰寫您自己的方法，以 GetHashCode 更密切地表示該型別的雜湊碼概念。In either case, consider writing your own implementation of the GetHashCode method that more closely represents the concept of a hash code for the type.

如需詳細資訊，請參閱 Object.GetHashCode 和System.Collections.Hashtable。For more information, see Object.GetHashCode, and System.Collections.Hashtable.

的注意事項 Windows 執行階段Windows RuntimeNotes for the Windows 執行階段Windows Runtime

當您 GetHashCode 在結構上呼叫方法時 Windows 執行階段Windows Runtime ，它會為不會覆寫的實數值型別提供預設行為 GetHashCode 。When you call the GetHashCode method on a Windows 執行階段Windows Runtime structure, it provides the default behavior for value types that don't override GetHashCode. 這是 .NET Framework 為 (提供的支援的一部分， Windows 執行階段Windows Runtime 請參閱 .NET Framework Microsoft Store 應用程式的支援和 Windows 執行階段) 。This is part of the support that the .NET Framework provides for the Windows 執行階段Windows Runtime (see .NET Framework Support for Windows Store Apps and Windows Runtime). Windows 執行階段Windows Runtime 結構無法覆寫 GetHashCode ，即使它們是使用 c # 或 Visual Basic 所撰寫，因為它們不能有方法。structures can't override GetHashCode, even if they're written with C# or Visual Basic, because they can't have methods. (此外，本身的結構 Windows 執行階段Windows Runtime 並不會繼承 ValueType 。 ) 不過， ToString Equals GetHashCode 當您在 c # 或 Visual Basic 程式碼中使用它們時，它們看起來會有、和方法，而 .NET Framework 會提供這些方法的預設行為。(In addition, structures in the Windows 執行階段Windows Runtime itself don't inherit ValueType.) However, they appear to have ToString, Equals, and GetHashCode methods when you use them in your C# or Visual Basic code, and the .NET Framework provides the default behavior for these methods.

適用於