C# | Insert into OrderedDictionary with key and value at specified index

OrderedDictionary.Insert(Int32, Object, Object) method is used to insert a new entry into the OrderedDictionary collection with the specified key and value at the specified index.

Syntax:

public void Insert (int index, object key, object value);

Parameters:

index : It is the zero-based index at which the element should be inserted.
key : It is the key of the entry to add.
value : It is the value of the entry to add. The value can be null.

Exceptions:

• NotSupportedException : If the OrderedDictionary collection is read-only.
• ArgumentOutOfRangeException : If the index is out of range.

Below given are some examples to understand the implementation in a better way:

Example 1:

// C# code to insert entry into
// OrderedDictionary with key and
// value at the specified index
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 number of element initially
        Console.WriteLine("Number of elements are : "
                                     + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);

        // Inserting entry into OrderedDictionary
        // with key and value at the specified index
        myDict.Insert(2, "Geeks", "Noida");

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : "
                                      + myDict.Count);

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

Output:

Number of elements are : 5
key1 -- value1
key2 -- value2
key3 -- value3
key4 -- value4
key5 -- value5
Number of elements are : 6
key1 -- value1
key2 -- value2
Geeks -- Noida
key3 -- value3
key4 -- value4
key5 -- value5

Example 2:

// C# code to insert entry into
// OrderedDictionary with key and
// value at the specified index
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("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : "
                                      + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);

        // Inserting entry into OrderedDictionary
        // with key and value at the specified index
        // This should raise "ArgumentOutOfRangeException"
        // as index is out of range
        myDict.Insert(10, "E", "Elephant");

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : "
                                      + myDict.Count);

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

Runtime Error:

Unhandled Exception:
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: index

Note:

• If the index parameter is equal to the number of entries in the OrderedDictionary collection, the key and value parameters are appended to the end of the collection.
• Entries that follow the insertion point move down to accommodate the new entry and the indexes of the moved entries are also updated.

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.ordereddictionary.insert?view=netframework-4.7.2