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

Definition

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);

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.

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;
        }
    }
}

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

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, 1.5, 1.6, 2.0, 2.1
UWP 10.0

See also