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IEqualityComparer.GetHashCode Method (Object)

 

Returns a hash code for the specified object.

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

int GetHashCode(
	object obj
)

Parameters

obj
Type: System.Object

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

Return Value

Type: System.Int32

A hash code for the specified object.

Exception Condition
ArgumentNullException

The type of obj is a reference type and obj is null.

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();
    }
}

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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