# ValueType.GetHashCode Method

## Definition

Returns the hash code for this instance.

``````public:
override int GetHashCode();``````
``public override int GetHashCode ();``
``override this.GetHashCode : unit -> int``
``Public Overrides Function GetHashCode () As Integer``

#### Returns

Int32

A 32-bit signed integer that is the hash code for this instance.

## Examples

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
``````

## Remarks

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.