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IComparer<T>.Compare(T, T) Method

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Definition

Namespace:
System.Collections.Generic
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll

Compares two objects and returns a value indicating whether one is less than, equal to, or greater than the other.

public:
 int Compare(T x, T y);
public int Compare (T x, T y);
public int Compare (T? x, T? y);
abstract member Compare : 'T * 'T -> int
Public Function Compare (x As T, y As T) As Integer

Parameters

x
T

The first object to compare.

y
T

The second object to compare.

Returns

Int32

A signed integer that indicates the relative values of x and y, as shown in the following table.

Value Meaning
Less than zero x is less than y.
Zero x equals y.
Greater than zero x is greater than y.

Examples

The following example implements the IComparer<T> interface to compare objects of type Box according to their dimensions. This example is part of a larger example provided for the Comparer<T> class.

// This class is not demonstrated in the Main method
// and is provided only to show how to implement
// the interface. It is recommended to derive
// from Comparer<T> instead of implementing IComparer<T>.
public class BoxComp : IComparer<Box>
{
    // Compares by Height, Length, and Width.
    public int Compare(Box x, Box y)
    {
        if (x.Height.CompareTo(y.Height) != 0)
        {
            return x.Height.CompareTo(y.Height);
        }
        else if (x.Length.CompareTo(y.Length) != 0)
        {
            return x.Length.CompareTo(y.Length);
        }
        else if (x.Width.CompareTo(y.Width) != 0)
        {
            return x.Width.CompareTo(y.Width);
        }
        else
        {
            return 0;
        }
    }
}

' This class is not demonstrated in the Main method
' and is provided only to show how to implement
' the interface. It is recommended to derive
' from Comparer<T> instead of implementing IComparer<T>.
Public Class BoxComp
    Implements IComparer(Of Box)
    ' Compares by Height, Length, and Width.
    Public Function Compare(ByVal x As Box, ByVal y As Box) As Integer Implements _
                                                IComparer(Of Box).Compare
        If x.Height.CompareTo(y.Height) <> 0 Then
            Return x.Height.CompareTo(y.Height)
        ElseIf x.Length.CompareTo(y.Length) <> 0 Then
            Return x.Length.CompareTo(y.Length)
        ElseIf x.Width.CompareTo(y.Width) <> 0 Then
            Return x.Width.CompareTo(y.Width)
        Else
            Return 0
        End If
    End Function
End Class

Remarks

Implement this method to provide a customized sort order comparison for type T.

Comparing null with any reference type is allowed and does not generate an exception. A null reference is considered to be less than any reference that is not null.

Applies to

See also