IEqualityComparer.Equals(Object, Object) Method

Reference

Definition

Namespace:: System.Collections

Assemblies:: mscorlib.dll, System.Runtime.dll

Assemblies:: netstandard.dll, System.Runtime.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Determines whether the specified objects are equal.

public:
 bool Equals(System::Object ^ x, System::Object ^ y);

public bool Equals(object x, object y);

public bool Equals(object? x, object? y);

abstract member Equals : obj * obj -> bool

Public Function Equals (x As Object, y As Object) As Boolean

Parameters

x: Object

The first object to compare.

y: Object

The second object to compare.

Returns

Boolean

true if the specified objects are equal; otherwise, false.

Exceptions

ArgumentException

x and y are of different types and neither one can handle comparisons with the other.

Examples

The following code example demonstrates the implementation of a case-insensitive IEqualityComparer. In this example, the CaseInsensitiveComparer.Compare method is used to determine whether two objects are equal, based on the provided CultureInfo.

ref class myCultureComparer : IEqualityComparer
{
private:
    CaseInsensitiveComparer^ myComparer;

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

    myCultureComparer(CultureInfo^ myCulture)
    {
        myComparer = gcnew CaseInsensitiveComparer(myCulture);
    }

    virtual bool Equals(Object^ x, Object^ y) 
    {
        if (myComparer->Compare(x, y) == 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    virtual int GetHashCode(Object^ obj)
    {
        return obj->ToString()->ToLower()->GetHashCode();
    }
};

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)
    {
        return myComparer.Compare(x, y) == 0;
    }

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

Public Class myCultureComparer
    Implements IEqualityComparer

    Dim myComparer As CaseInsensitiveComparer

    Public Sub New()
        myComparer = CaseInsensitiveComparer.DefaultInvariant
    End Sub

    Public Sub New(ByVal myCulture As CultureInfo)
        myComparer = New CaseInsensitiveComparer(myCulture)
    End Sub

    Public Function Equals1(ByVal x As Object, ByVal y As Object) _
        As Boolean Implements IEqualityComparer.Equals

        Return myComparer.Compare(x, y) = 0
    End Function

    Public Function GetHashCode1(ByVal obj As Object) _
        As Integer Implements IEqualityComparer.GetHashCode
        Return obj.ToString().ToLower().GetHashCode()
    End Function
End Class

Remarks

Implement this method to provide a customized equality comparison for objects.

Notes to Implementers

The Equals(Object, Object) method is reflexive, symmetric, and transitive. That is, it returns true if used to compare an object with itself; true for two objects x and y if it is true for y and x; and true for two objects x and z if it is true for x and y and also true for y and z.

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

Applies to

Product	Versions
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP	10.0

Share via