C# | Check if OrderedDictionary collection contains a specific key

Last Updated : 01 Feb, 2019

OrderedDictionary.Contains(Object) method is used to check whether the OrderedDictionary collection contains a specific key or not. Syntax:

public bool Contains (object key);

Here, key is the key to locate in the OrderedDictionary collection. Return Value: This method returns True if the OrderedDictionary collection contains an element with the specified key, otherwise, False. Below given are some examples to understand the implementation in a better way: Example 1:

CSHARP

// C# code to check if OrderedDictionary
// collection contains a specific key
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver method
    public static void Main()
    {

        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();

        // Adding key and value in myDict
        myDict.Add("key1", "value1");
        myDict.Add("key2", "value2");
        myDict.Add("key3", "value3");
        myDict.Add("key4", "value4");
        myDict.Add("key5", "value5");

        // Checking if OrderedDictionary
        // collection contains a specific key
        Console.WriteLine(myDict.Contains("Key6"));
    }
}

Output:

False

Example 2:

CSHARP

// C# code to check if OrderedDictionary
// collection contains a specific key
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver method
    public static void Main()
    {

        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();

        // Adding key and value in myDict
        myDict.Add("key1", "value1");
        myDict.Add("key2", "value2");
        myDict.Add("key3", "value3");
        myDict.Add("key4", "value4");
        myDict.Add("key5", "value5");

        // Displaying the key/value pairs in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " --> " + de.Value);

        // Checking if OrderedDictionary collection
        // contains a specific key
        if (myDict.Contains("key4"))
            myDict.Remove("key4");

        // Displaying the key/value pairs in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " --> " + de.Value);
    }
}

Output:

key1 --> value1
key2 --> value2
key3 --> value3
key4 --> value4
key5 --> value5
key1 --> value1
key2 --> value2
key3 --> value3
key5 --> value5

Note: Using the Item[Object] property can return a null value if the key does not exist or if the key is null. Use the Contains method to determine if a specific key exists in the OrderedDictionary collection. Reference: https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.ordereddictionary.contains?view=netframework-4.7.2

C# | Check if SortedDictionary contains the specified key or not

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C# | Check if OrderedDictionary collection contains a specific key

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