Array.Sort(Of TKey, TValue) Method (TKey(), TValue())

July 28, 2014

Sorts a pair of Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the IComparable(Of T) generic interface implementation of each key.

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

'Declaration
Public Shared Sub Sort(Of TKey, TValue) ( _
	keys As TKey(), _
	items As TValue() _
)

Type Parameters

TKey

The type of the elements of the key array.

TValue

The type of the elements of the items array.

Parameters

keys
Type: TKey ()
The one-dimensional, zero-based Array that contains the keys to sort.
items
Type: TValue ()
The one-dimensional, zero-based Array that contains the items that correspond to the keys in keys, or Nothing to sort only keys.

ExceptionCondition
ArgumentNullException

keys is Nothing.

ArgumentException

items is not Nothing, and the lower bound of keys does not match the lower bound of items.

-or-

items is not Nothing, and the length of keys is greater than the length of items.

InvalidOperationException

One or more elements in the keysArray do not implement the IComparable(Of T) generic interface.

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

Each key in the keysArray must implement the IComparable(Of T) generic 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 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.

On average, this method is an O(n log n) operation, where n is the Length of array; in the worst case it is an O(n ^ 2) operation.

The following code example demonstrates the Sort(Of TKey, TValue)(TKey(), TValue()), Sort(Of TKey, TValue)(TKey(), TValue(), IComparer(Of TKey)), Sort(Of TKey, TValue)(TKey(), TValue(), Int32, Int32), and Sort(Of TKey, TValue)(TKey(), TValue(), Int32, Int32, IComparer(Of TKey)) generic method overloads, for sorting pairs of arrays that represent keys and values.

The code example defines an alternative comparer for strings, named ReverseCompare, which implements the IComparer<string> (IComparer(Of String) in Visual Basic, IComparer<String^> in Visual C++) generic interface. The comparer calls the CompareTo(String) method, reversing the order of the comparands so that the strings sort high-to-low instead of low-to-high.

The code example creates and displays an array of dinosaur names (the keys) and an array of integers representing the maximum length of each dinosaur in meters (the values). The arrays are then sorted and displayed several times:

NoteNote:

The calls to the generic methods do not look any different from calls to their nongeneric counterparts, because Visual Basic, C#, and C++ infer the type of the generic type parameter from the type of the first two arguments.


Imports System.Collections.Generic

Public Class ReverseComparer
   Implements IComparer(Of String)

   Public Function Compare(ByVal x As String, _
       ByVal y As String) As Integer _
       Implements IComparer(Of String).Compare

      ' Compare y and x in reverse order.
      Return y.CompareTo(x)

   End Function
End Class

Public Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Dim dinosaurs() As String = { _
          "Seismosaurus", _
          "Chasmosaurus", _
          "Coelophysis", _
          "Mamenchisaurus", _
          "Caudipteryx", _
          "Cetiosaurus"}

      Dim dinosaurSizes() As Integer = {40, 5, 3, 22, 1, 18}

      outputBlock.Text &= vbCrLf
      For i As Integer = 0 To dinosaurs.Length - 1
         outputBlock.Text &= String.Format("{0}: up to {1} meters long.", _
             dinosaurs(i), dinosaurSizes(i)) & vbCrLf
      Next

      outputBlock.Text &= String.Format(vbLf & _
          "Sort(dinosaurs, dinosaurSizes)") & vbCrLf
      Array.Sort(dinosaurs, dinosaurSizes)

      outputBlock.Text &= vbCrLf
      For i As Integer = 0 To dinosaurs.Length - 1
         outputBlock.Text &= String.Format("{0}: up to {1} meters long.", _
             dinosaurs(i), dinosaurSizes(i)) & vbCrLf
      Next

      Dim rc As New ReverseComparer()

      outputBlock.Text &= String.Format(vbLf & _
          "Sort(dinosaurs, dinosaurSizes, rc)") & vbCrLf
      Array.Sort(dinosaurs, dinosaurSizes, rc)

      outputBlock.Text &= vbCrLf
      For i As Integer = 0 To dinosaurs.Length - 1
         outputBlock.Text &= String.Format("{0}: up to {1} meters long.", _
             dinosaurs(i), dinosaurSizes(i)) & vbCrLf
      Next

      outputBlock.Text &= String.Format(vbLf & _
          "Sort(dinosaurs, dinosaurSizes, 3, 3)") & vbCrLf
      Array.Sort(dinosaurs, dinosaurSizes, 3, 3)

      outputBlock.Text &= vbCrLf
      For i As Integer = 0 To dinosaurs.Length - 1
         outputBlock.Text &= String.Format("{0}: up to {1} meters long.", _
             dinosaurs(i), dinosaurSizes(i)) & vbCrLf
      Next

      outputBlock.Text &= String.Format(vbLf & _
          "Sort(dinosaurs, dinosaurSizes, 3, 3, rc)") & vbCrLf
      Array.Sort(dinosaurs, dinosaurSizes, 3, 3, rc)

      outputBlock.Text &= vbCrLf
      For i As Integer = 0 To dinosaurs.Length - 1
         outputBlock.Text &= String.Format("{0}: up to {1} meters long.", _
             dinosaurs(i), dinosaurSizes(i)) & vbCrLf
      Next

   End Sub

End Class

' This code example produces the following output:
'
'Seismosaurus: up to 40 meters long.
'Chasmosaurus: up to 5 meters long.
'Coelophysis: up to 3 meters long.
'Mamenchisaurus: up to 22 meters long.
'Caudipteryx: up to 1 meters long.
'Cetiosaurus: up to 18 meters long.
'
'Sort(dinosaurs, dinosaurSizes)
'
'Caudipteryx: up to 1 meters long.
'Cetiosaurus: up to 18 meters long.
'Chasmosaurus: up to 5 meters long.
'Coelophysis: up to 3 meters long.
'Mamenchisaurus: up to 22 meters long.
'Seismosaurus: up to 40 meters long.
'
'Sort(dinosaurs, dinosaurSizes, rc)
'
'Seismosaurus: up to 40 meters long.
'Mamenchisaurus: up to 22 meters long.
'Coelophysis: up to 3 meters long.
'Chasmosaurus: up to 5 meters long.
'Cetiosaurus: up to 18 meters long.
'Caudipteryx: up to 1 meters long.
'
'Sort(dinosaurs, dinosaurSizes, 3, 3)
'
'Seismosaurus: up to 40 meters long.
'Mamenchisaurus: up to 22 meters long.
'Coelophysis: up to 3 meters long.
'Caudipteryx: up to 1 meters long.
'Cetiosaurus: up to 18 meters long.
'Chasmosaurus: up to 5 meters long.
'
'Sort(dinosaurs, dinosaurSizes, 3, 3, rc)
'
'Seismosaurus: up to 40 meters long.
'Mamenchisaurus: up to 22 meters long.
'Coelophysis: up to 3 meters long.
'Chasmosaurus: up to 5 meters long.
'Cetiosaurus: up to 18 meters long.
'Caudipteryx: up to 1 meters long.


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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