GetHashCode Method
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IEqualityComparer.GetHashCode Method

Returns a hash code for the specified object.

Namespace: System.Collections
Assembly: mscorlib (in mscorlib.dll)

int GetHashCode (
	Object obj
)
int GetHashCode (
	Object obj
)
function GetHashCode (
	obj : Object
) : int
Not applicable.

Parameters

obj

The Object for which a hash code is to be returned.

Return Value

A hash code for the specified object.

Exception typeCondition

ArgumentNullException

The type of obj is a reference type and obj is a null reference (Nothing in Visual Basic).

Implement this method to provide customized hash codes for objects,corresponding to the customized equality comparison provided by the Equals method.

Notes to Implementers: Implementations are required to ensure that if the Equals method returns true for two objects x and y, then the value returned by the GetHashCode method for x must equal the value returned for y.

The following code example demonstrates the implementation of a case-insensitive IEqualityComparer. In this example, the GetHashCode method returns the hash code provided by the Object type.

class myCultureComparer : IEqualityComparer
{
    public CaseInsensitiveComparer myComparer;

    public myCultureComparer()
    {
        myComparer = CaseInsensitiveComparer.DefaultInvariant;
    }

    public myCultureComparer(CultureInfo myCulture)
    {
        myComparer = new CaseInsensitiveComparer(myCulture);
    }

    public new bool Equals(object x, object y)
    {
        if (myComparer.Compare(x, y) == 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public int GetHashCode(object obj)
    {
        return obj.ToString().ToLower().GetHashCode();
    }
}

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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