Array.Sort Method (Array, Array, Int32, Int32, IComparer)
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
public static void Sort( Array keys, Array items, int index, int length, IComparer comparer )
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-
null to sort only the keys Array.
- index
- Type: System.Int32
The starting index of the range to sort.
- length
- Type: System.Int32
The number of elements in the range to sort.
- comparer
- Type: System.Collections.IComparer
The IComparer implementation to use when comparing elements.
-or-
null to use the IComparable implementation of each element.
| Exception | Condition |
|---|---|
| ArgumentNullException | keys is null. |
| RankException | The keys Array is multidimensional. -or- The items Array is multidimensional. |
| ArgumentOutOfRangeException | index is less than the lower bound of keys. -or- length is less than zero. |
| ArgumentException | items is not null, and the lower bound of keys does not match the lower bound of items. -or- items is not null, and the length of keys is greater than the length of items. -or- index and length do not specify a valid range in the keys Array. -or- items is not null, and index and length do not specify a valid range in the items Array. -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 null, 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 null, each key within the specified range of elements 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.
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 length.
Notes to CallersThe .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 code 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.
using System; using System.Collections; public class SamplesArray { public class myReverserClass : IComparer { // Calls CaseInsensitiveComparer.Compare with the parameters reversed. int IComparer.Compare( Object x, Object y ) { return( (new CaseInsensitiveComparer()).Compare( y, x ) ); } } public static void Main() { // Creates and initializes a new Array and a new custom comparer. String[] myKeys = { "red", "GREEN", "YELLOW", "BLUE", "purple", "black", "orange" }; String[] myValues = { "strawberries", "PEARS", "LIMES", "BERRIES", "grapes", "olives", "cantaloupe" }; IComparer myComparer = new myReverserClass(); // Displays the values of the Array. Console.WriteLine( "The Array initially contains the following values:" ); PrintKeysAndValues( myKeys, myValues ); // Sorts a section of the Array using the default comparer. Array.Sort( myKeys, myValues, 1, 3 ); Console.WriteLine( "After sorting a section of the Array using the default comparer:" ); PrintKeysAndValues( myKeys, myValues ); // Sorts a section of the Array using the reverse case-insensitive comparer. Array.Sort( myKeys, myValues, 1, 3, myComparer ); Console.WriteLine( "After sorting a section of the Array using the reverse case-insensitive comparer:" ); PrintKeysAndValues( myKeys, myValues ); // Sorts the entire Array using the default comparer. Array.Sort( myKeys, myValues ); Console.WriteLine( "After sorting the entire Array using the default comparer:" ); PrintKeysAndValues( myKeys, myValues ); // Sorts the entire Array using the reverse case-insensitive comparer. Array.Sort( myKeys, myValues, myComparer ); Console.WriteLine( "After sorting the entire Array using the reverse case-insensitive comparer:" ); PrintKeysAndValues( myKeys, myValues ); } public static void PrintKeysAndValues( String[] myKeys, String[] myValues ) { for ( int i = 0; i < myKeys.Length; i++ ) { Console.WriteLine( " {0,-10}: {1}", myKeys[i], myValues[i] ); } Console.WriteLine(); } } /* This code produces the following output. The Array initially contains the following values: red : strawberries GREEN : PEARS YELLOW : LIMES BLUE : BERRIES purple : grapes black : olives orange : cantaloupe After sorting a section of the Array using the default comparer: red : strawberries BLUE : BERRIES GREEN : PEARS YELLOW : LIMES purple : grapes black : olives orange : cantaloupe After sorting a section of the Array using the reverse case-insensitive comparer: red : strawberries YELLOW : LIMES GREEN : PEARS BLUE : BERRIES purple : grapes black : olives orange : cantaloupe After sorting the entire Array using the default comparer: black : olives BLUE : BERRIES GREEN : PEARS orange : cantaloupe purple : grapes red : strawberries YELLOW : LIMES After sorting the entire Array using the reverse case-insensitive comparer: YELLOW : LIMES red : strawberries purple : grapes orange : cantaloupe GREEN : PEARS BLUE : BERRIES black : olives */
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.