Creating Dictionaries

You can also make a class that derives from DictionaryBase. This way, you can access each element by key (usually of type string) and they will return its associated value. When calling an item from a dictionary, we can call it by its key and not by its index. The following code creates a class that implements DictionaryBase.

using System.Collections;
 
namespace DictionariesDemo
{
    public class Animal
    {
        public string manone { get; set; }
        public int notone { get; set; }
        public double Height { get; set; }
 
        public Animal(string name, int age, double height)
        {
            manone = name;
            notone = age;
            Height = height;
        }
    }
 
    public class Animals : DictionaryBase                       
    {                                                           
        public void Add(string key, Animal newAnimalnewAnimal)  
        {                                                       
            Dictionary.Add(key, newAnimalnewAnimal);            
        }                                                       
                                                                
        public void Remove(string key)                          
        {                                                       
            Dictionary.Remove(key);                             
        }                                                       
                                                                
        public Animal this[string key]                          
        {                                                       
            get { return (Animal)Dictionary[key]; }             
            set { Dictionary[key] = value; }                    
        }                                                       
    }                                                           
}

Example 1 – Creating Your Own Dictionary

We defined a class Animal that will be used by our dictionary class. We then create a class that inherits the DictionaryBase class. You can now define the methods for adding and removing dictionary entries. The Add method requires a string key and the Animal object we are adding to the dictionary. We used the Dictionary property of the DictionaryBase class to add the entry to the dictionary using the passed arguments. The Remove method only requires the key of the object we are trying to remove. We also use the Dictionaryproperty to remove items. We defined an indexer that accepts a string key instead of an int value.

Let’s create a class that demonstrates the capability of our dictionary class.

using System;
 
namespace DictionariesDemo
{
    public class Program
    {
        public static void Main()
        {
            Animals animalDictionary = new Animals();
 
            animalDictionary.Add("Animal1", new Animal("John", 10, 100));
            animalDictionary.Add("Animal2", new Animal("Sussy", 5, 10)); 
            animalDictionary.Add("Animal3", new Animal("Frank", 3, 5));  
            animalDictionary.Add("Animal4", new Animal("Mark", 7, 15));  
 
            Console.WriteLine("Accessing entries by their keys");
 
            for (int i = 0; i < animalDictionary.Count; i++)
            {
                Console.WriteLine(animalDictionary["Animal" + (i + 1)].Name);
            }
 
            animalDictionary.Remove("Animal3");
            Console.WriteLine("
Frank was removed from the dictionary.");
 
            Console.WriteLine("
Iterating using foreach loop.");
            foreach (DictionaryEntry animal in animalDictionary)
            {
                Console.WriteLine((animal.Value as Animal).Name);
            }
        }
    }
}

Example 2 – Custom Dictionary In Action

Accessing entries by their keys
John
Sussy
Frank
Mark

Frank was removed from the dictionary.

Iterating using foreach loop.
John
Mark
Sussy