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

Definition

When overridden in a derived class, performs a comparison of two objects of the same type and returns a value indicating whether one object is less than, equal to, or greater than the other.

C#
public abstract int Compare(T x, T y);
C#
public abstract int Compare(T? x, T? y);

Parameters

x
T

The first object to compare.

y
T

The second object to compare.

Returns

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.

Implements

Exceptions

Type T does not implement either the IComparable<T> generic interface or the IComparable interface.

Examples

The following example defines a comparer of Box objects that can be used instead of the default comparer. This example is part of a larger example provided for the Comparer<T> class.

C#
public class BoxLengthFirst : Comparer<Box>
{
    // Compares by Length, Height, and Width.
    public override int Compare(Box x, Box y)
    {
        if (x.Length.CompareTo(y.Length) != 0)
        {
            return x.Length.CompareTo(y.Length);
        }
        else if (x.Height.CompareTo(y.Height) != 0)
        {
            return x.Height.CompareTo(y.Height);
        }
        else if (x.Width.CompareTo(y.Width) != 0)
        {
            return x.Width.CompareTo(y.Width);
        }
        else
        {
            return 0;
        }
    }
}

Remarks

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

Notes to Implementers

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.

For information on culture-specific comparisons, see the System.Globalization namespace and Globalization and Localization.

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
.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, 1.6, 2.0, 2.1
UWP 10.0

See also