Export (0) Print
Expand All

Array.Sort Method (Array, Array, IComparer)

Sorts a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer.

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

static member Sort : 
        keys:Array * 
        items:Array * 
        comparer:IComparer -> unit

Parameters

keys
Type: System.Array

The one-dimensional Array that contains the keys to sort.

items
Type: System.Array

The one-dimensional Array that contains the items that correspond to each of the keys in the keys Array.

-or-

a null reference (Nothing in Visual Basic) to sort only the keys Array.

comparer
Type: System.Collections.IComparer

The IComparer implementation to use when comparing elements.

-or-

a null reference (Nothing in Visual Basic) to use the IComparable implementation of each element.

ExceptionCondition
ArgumentNullException

keys is a null reference (Nothing in Visual Basic).

RankException

The keys Array is multidimensional.

-or-

The items Array is multidimensional.

ArgumentException

items is not a null reference (Nothing in Visual Basic), and the length of keys is greater than the length of items.

-or-

The implementation of comparer caused an error during the sort. For example, comparer might not return 0 when comparing an item with itself.

InvalidOperationException

comparer is a null reference (Nothing in Visual Basic), and one or more elements in the keys Array do not implement the IComparable interface.

Each key in the keys Array has a corresponding item in the items Array. When a key is repositioned during the sorting, the corresponding item in the items Array is similarly repositioned. Therefore, the items Array is sorted according to the arrangement of the corresponding keys in the keys Array.

If comparer is a null reference (Nothing in Visual Basic), each key in the keys Array must implement the IComparable interface to be capable of comparisons with every other key.

You can sort if there are more items than keys, but the items that have no corresponding keys will not be sorted. You cannot sort if there are more keys than items; doing this throws an ArgumentException.

If the sort is not successfully completed, the results are undefined.

The .NET Framework includes predefined IComparer implementations listed in the following table.

Implementation

Description

System.Collections.CaseInsensitiveComparer

Compares any two objects, but performs a case-insensitive comparison of strings.

Comparer.Default

Compares any two objects by using the sorting conventions of the current culture.

Comparer.DefaultInvariant

Compares any two objects by using the sorting conventions of the invariant culture.

Comparer(T).Default

Compares two objects of type T by using the type's default sort order.

You can also support custom comparisons by providing an instance of your own IComparer implementation to the comparer parameter. The example does this by defining an IComparer implementation that reverses the default sort order and performs case-insensitive string comparison.

This method uses the introspective sort (introsort) algorithm as follows:

  • If the partition size is fewer than 16 elements, it uses an insertion sort algorithm.

  • If the number of partitions exceeds 2 * LogN, where N is the range of the input array, it uses a Heapsort algorithm.

  • Otherwise, it uses a Quicksort algorithm.

This implementation performs an unstable sort; that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal.

For arrays that are sorted by using the Heapsort and Quicksort algorithms, in the worst case, this method is an O(n log n) operation, where n is the Length of keys.

Notes to Callers

The .NET Framework 4 and earlier versions used only the Quicksort algorithm. Quicksort identifies invalid comparers in some situations in which the sorting operation throws an IndexOutOfRangeException exception, and throws an ArgumentException exception to the caller. Starting with the .NET Framework 4.5, it is possible that sorting operations that previously threw ArgumentException will not throw an exception, because the insertion sort and heapsort algorithms do not detect an invalid comparer. For the most part, this applies to arrays with fewer than 16 elements.

The following example shows how to sort two associated arrays where the first array contains the keys and the second array contains the values. Sorts are done using the default comparer and a custom comparer that reverses the sort order. Note that the result might vary depending on the current CultureInfo.

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Show:
© 2014 Microsoft