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Array.Sort<T> Method (T[])

Sorts the elements in an entire Array using the IComparable<T> generic interface implementation of each element of the Array.

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

public static void Sort<T>(
	T[] array

Type Parameters


The type of the elements of the array.


Type: T[]

The one-dimensional, zero-based Array to sort.


array is null.


One or more elements in array do not implement the IComparable<T> generic interface.

Each element of array must implement the IComparable<T> generic interface to be capable of comparisons with every other element in array.

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 the Length of array.

The following code example demonstrates the Sort<T>(T[]) generic method overload and the BinarySearch<T>(T[], T) generic method overload. An array of strings is created, in no particular order.

The array is displayed, sorted, and displayed again.


The calls to the Sort and BinarySearch 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 argument. If you use the Ildasm.exe (IL Disassembler) to examine the Microsoft intermediate language (MSIL), you can see that the generic methods are being called.

The BinarySearch<T>(T[], T) generic method overload is then used to search for two strings, one that is not in the array and one that is. The array and the return value of the BinarySearch method are passed to the ShowWhere generic method, which displays the index value if the string is found, and otherwise the elements the search string would fall between if it were in the array. The index is negative if the string is not n the array, so the ShowWhere method takes the bitwise complement (the ~ operator in C# and Visual C++, Xor -1 in Visual Basic) to obtain the index of the first element in the list that is larger than the search string.

using System;
using System.Collections.Generic;

public class Example
    public static void Main()
        string[] dinosaurs = {"Pachycephalosaurus", 

        foreach( string dinosaur in dinosaurs )


        foreach( string dinosaur in dinosaurs )

        Console.WriteLine("\nBinarySearch for 'Coelophysis':");
        int index = Array.BinarySearch(dinosaurs, "Coelophysis");
        ShowWhere(dinosaurs, index);

        Console.WriteLine("\nBinarySearch for 'Tyrannosaurus':");
        index = Array.BinarySearch(dinosaurs, "Tyrannosaurus");
        ShowWhere(dinosaurs, index);

    private static void ShowWhere<T>(T[] array, int index)
        if (index<0)
            // If the index is negative, it represents the bitwise 
            // complement of the next larger element in the array. 
            index = ~index;

            Console.Write("Not found. Sorts between: ");

            if (index == 0)
                Console.Write("beginning of array and ");
                Console.Write("{0} and ", array[index-1]);

            if (index == array.Length)
                Console.WriteLine("end of array.");
                Console.WriteLine("{0}.", array[index]);
            Console.WriteLine("Found at index {0}.", index);

/* This code example produces the following output:




BinarySearch for 'Coelophysis':
Not found. Sorts between: Amargasaurus and Deinonychus.

BinarySearch for 'Tyrannosaurus':
Found at index 5.

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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