SortedDictionary<TKey,TValue>.IDictionary.Contains(Object) Method

Definition

Namespace:

System.Collections.Generic

Assemblies:

netstandard.dll, System.Collections.dll

Source:

SortedDictionary.cs

Determines whether the IDictionary contains an element with the specified key.

C#

bool IDictionary.Contains(object key);

Parameters

key

Object

The key to locate in the IDictionary.

Returns

Boolean

true if the IDictionary contains an element with the key; otherwise, false.

Implements

Contains(Object)

Exceptions

ArgumentNullException

key is null.

Examples

The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a SortedDictionary<TKey,TValue>. The example demonstrates that the method returns false if a key of the wrong data type is supplied.

The code example is part of a larger example, including output, provided for the IDictionary.Add method.

C#

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new sorted dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new SortedDictionary<string, string>();

        // Add some elements to the dictionary. There are no
        // duplicate keys, but some of the values are duplicates.
        // IDictionary.Add throws an exception if incorrect types
        // are supplied for key or value.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");

C#

// Contains can be used to test keys before inserting
// them.
if (!openWith.Contains("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}",
        openWith["ht"]);
}

// IDictionary.Contains returns false if the wrong data
// type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}",
    openWith.Contains(29.7));

C#

    }
}

Remarks

This method returns false if key is of a type that is not assignable to the key type TKey of the SortedDictionary<TKey,TValue>.

This method is an O(log n) operation, where n is Count.

Applies to