IStructuralComparable::CompareTo Method (Object^, IComparer^)


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Determines whether the current collection object precedes, occurs in the same position as, or follows another object in the sort order.

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

int CompareTo(
	Object^ other,
	IComparer^ comparer


Type: System::Object^

The object to compare with the current instance.

Type: System.Collections::IComparer^

An object that compares members of the current collection object with the corresponding members of other.

Return Value

Type: System::Int32

An integer that indicates the relationship of the current collection object to other, as shown in the following table.

Return value



The current instance precedes other.


The current instance and other are equal.


The current instance follows other.

Exception Condition

This instance and other are not the same type.

The CompareTo method supports custom structural comparison and sorting of array and tuple objects. The CompareTo method calls the comparer object's IComparer::Compare method to compare individual array elements or tuple components, starting with the first element or component. The individual calls to IComparer::Compare end and the CompareTo method returns a value when one of the following conditions becomes true:

The following example creates an array of Tuple<T1, T2, T3, T4, T5, T6> objects that contains population data for three U.S. cities from 1960 to 2000. The sextuple's first component is the city name. The remaining five components represent the population at ten-year intervals from 1960 to 2000.

The PopulationComparer class provides an IComparer implementation that allows the array of sextuples to be sorted by any one of its components. Two values are provided to the PopulationComparer class in its constructor: the position of the component that defines the sort order, and a Boolean value that indicates whether the tuple objects should be sorted in ascending or descending order.

The example then displays the elements in the array in unsorted order, sorts them by the third component (the population in 1970) and displays them, and then sorts them by the sixth component (the population in 2000) and displays them. Note that the example does not directly call the IStructuralComparable::CompareTo implementation. The method is called implicitly by the Sort(Array^, IComparer^) method for each tuple object in the array.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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