C# | Insert a new entry in OrderedDictionary with specified key and value

OrderedDictionary.Insert(Int32, Object, Object) Method is used to inserts 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 of type System.Int32 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:

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

Below programs illustrate the use of above-discussed method:

Example 1:

// C# code to add a new entry into the
// OrderedDictionary collection with
// the specified 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");

        Console.WriteLine("Before Updation: ");

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

        // using Insert(Int32, Object, Object) Method
        // to add a new entry at index 5
        myDict.Insert(5, "key6", "value6");

        Console.WriteLine("\nAfter Updation: ");

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

Output:

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

After Updation: 
key1 --> value1
key2 --> value2
key3 --> value3
key4 --> value4
key5 --> value5
key6 --> value6

Example 2:

// C# code to add a new entry into the
// OrderedDictionary collection with
// the specified 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("1", "C");
        myDict.Add("2", "C++");
        myDict.Add("3", "Java");
        myDict.Add("4", "Python");
        myDict.Add("5", "C#");

        Console.WriteLine("Before Updation: ");

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

        // using Insert(Int32, Object, Object) Method
        // this will give error as index is out of range
        // here indexing is zero-based
        myDict.Insert(6, "6", "HTML");

        Console.WriteLine("\nAfter Updation: ");

        // Displaying the key/value pairs 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:

• The key and value parameters will be appended to the end of the collection if the index parameter is equal to the number of entries in the OrderedDictionary 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