Returns the hash code for this instance.
Assembly: mscorlib (in mscorlib.dll)
Public Overrides Function GetHashCode As [%$TOPIC/y3509fc2_en-us_VS_110_1_0_0_0_0%]public override [%$TOPIC/y3509fc2_en-us_VS_110_1_0_1_0_0%] GetHashCode()public:
virtual [%$TOPIC/y3509fc2_en-us_VS_110_1_0_2_0_0%] GetHashCode() overrideabstract GetHashCode : unit -> [%$TOPIC/y3509fc2_en-us_VS_110_1_0_3_0_0%]
override GetHashCode : unit -> [%$TOPIC/y3509fc2_en-us_VS_110_1_0_3_0_1%]The GetHashCode method applies to types derived from ValueType. One or more fields of the derived type is used to calculate the return value. 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. 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. 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.
For more information, see ObjectGetHashCode, and System.CollectionsHashtable.
Notes for the Windows Runtime
When you call the GetHashCode method on a Windows Runtime structure, it provides the default behavior for value types that don’t override GetHashCode. This is part of the support that the .NET Framework provides for the Windows Runtime (see .NET Framework Support for Windows Store Apps and Windows Runtime). Windows Runtime structures can’t override GetHashCode, even if they’re written with C# or Visual Basic, because they can’t have methods. (In addition, structures in the 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.
The following example demonstrates how the GetHashCode method can be overridden by a derived value type.
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 Structurepublic 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 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();
}
};Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
