SortedList<TKey, TValue> Constructor (Int32, IComparer<TKey>)


The .NET API Reference documentation has a new home. Visit the .NET API Browser on to see the new experience.

Initializes a new instance of the SortedList<TKey, TValue> class that is empty, has the specified initial capacity, and uses the specified IComparer<T>.

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

public SortedList(
	int capacity,
	IComparer<TKey> comparer


Type: System.Int32

The initial number of elements that the SortedList<TKey, TValue> can contain.

Type: System.Collections.Generic.IComparer<TKey>

The IComparer<T> implementation to use when comparing keys.


null to use the default Comparer<T> for the type of the key.

Exception Condition

capacity is less than zero.

Every key in a SortedList<TKey, TValue> must be unique according to the specified comparer.

The capacity of a SortedList<TKey, TValue> is the number of elements that the SortedList<TKey, TValue> can hold before resizing. As elements are added to a SortedList<TKey, TValue>, the capacity is automatically increased as required by reallocating the internal array.

If the size of the collection can be estimated, specifying the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the SortedList<TKey, TValue>.

The capacity can be decreased by calling TrimExcess or by setting the Capacity property explicitly. Decreasing the capacity reallocates memory and copies all the elements in the SortedList<TKey, TValue>.

This constructor is an O(n) operation, where n is capacity.

The following code example creates a sorted list with an initial capacity of 5 and a case-insensitive comparer for the current culture. The example adds four elements, some with lower-case keys and some with upper-case keys. The example then attempts to add an element with a key that differs from an existing key only by case, catches the resulting exception, and displays an error message. Finally, the example displays the elements in case-insensitive sort order.

using System;
using System.Collections.Generic;

public class Example
    public static void Main()
        // Create a new sorted list of strings, with string keys, an
        // initial capacity of 5, and a case-insensitive comparer.
        SortedList<string, string> openWith = 
                      new SortedList<string, string>(5, 

        // Add 4 elements to the list. 
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("DIB", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");

        // Try to add a fifth element with a key that is the same 
        // except for case; this would be allowed with the default
        // comparer.
            openWith.Add("BMP", "paint.exe");
        catch (ArgumentException)
            Console.WriteLine("\nBMP is already in the sorted list.");

        // List the contents of the sorted list.
        foreach( KeyValuePair<string, string> kvp in openWith )
            Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, 

/* This code example produces the following output:

BMP is already in the sorted list.

Key = bmp, Value = paint.exe
Key = DIB, Value = paint.exe
Key = rtf, Value = wordpad.exe
Key = txt, Value = notepad.exe

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
Return to top