C# | Copying the HybridDictionary entries to an Array Instance

HybridDictionary.CopyTo(Array, Int32) method is used to copy the HybridDictionary entries to a one-dimensional Array instance at the specified index.

Syntax:

public void CopyTo (Array array, int index);

Parameters:

array : The one-dimensional Array that is the destination of the DictionaryEntry objects copied from HybridDictionary. The Array must have zero-based indexing.

index : The zero-based index in array at which copying begins.

Exceptions:

• ArgumentNullException : If the array is null.
• ArgumentOutOfRangeException : If the index is less than zero.
• InvalidCastException : If the type of the source HybridDictionary cannot be cast automatically to the type of the destination array.
• ArgumentException : If array is multidimensional OR the number of elements in the source HybridDictionary is greater than the available space from arrayIndex to the end of the destination array.

Below programs illustrate the use of HybridDictionary.CopyTo(Array, Int32) method:

Example 1:

// C# code to copy the HybridDictionary
// entries to a one-dimensional Array
// instance at the specified index.
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a HybridDictionary named myDict
        HybridDictionary myDict = new HybridDictionary();

        // Adding key/value pairs in myDict
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
        myDict.Add("E", "Elephant");
        myDict.Add("F", "Fish");

        // Creating a one-dimensional Array named myArr
        DictionaryEntry[] myArr = new DictionaryEntry[myDict.Count];

        // copying the HybridDictionary entries
        // to a one-dimensional Array instance
        // at the specified index
        myDict.CopyTo(myArr, 0);

        for (int i = 0; i < myArr.Length; i++)
            Console.WriteLine(myArr[i].Key + " --> "
                                  + myArr[i].Value);
    }
}

Output:

A --> Apple
B --> Banana
C --> Cat
D --> Dog
E --> Elephant
F --> Fish

Example 2:

// C# code to copy the HybridDictionary
// entries to a one-dimensional Array
// instance at the specified index.
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a HybridDictionary named myDict
        HybridDictionary myDict = new HybridDictionary();

        // Adding key/value pairs in myDict
        myDict.Add("I", "first");
        myDict.Add("II", "second");
        myDict.Add("III", "third");
        myDict.Add("IV", "fourth");
        myDict.Add("V", "fifth");

        // Creating a one-dimensional Array named myArr
        DictionaryEntry[] myArr = new DictionaryEntry[myDict.Count];

        // copying the HybridDictionary entries
        // to a one-dimensional Array instance
        // at the specified index
        // This should raise "ArgumentOutOfRangeException"
        // as index is less than 0
        myDict.CopyTo(myArr, -2);

        for (int i = 0; i < myArr.Length; i++)
            Console.WriteLine(myArr[i].Key + " --> "
                                  + myArr[i].Value);
    }
}

Runtime Error:

Unhandled Exception:
System.ArgumentOutOfRangeException: Index is less than zero.
Parameter name: index

Note:

• The elements are copied to the Array in the same order in which the enumerator iterates through the HybridDictionary.
• To copy only the keys in the HybridDictionary, use HybridDictionary.Keys.CopyTo.
• To copy only the values in the HybridDictionary, use HybridDictionary.Values.CopyTo.
• This method is an O(n) operation, where n is Count.

Reference:

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