C# Dictionary

C# Dictionary

In C# the Dictionary is also another type of generic collection that stores key-value pairs. Dictionary also comes under System.Collections.Generic namespace. In a Dictionary collection key must be unique and cannot be null but values can be null or duplicated.

Let’s look at some code examples of Dictionary in C#.

 
using System;
using System.Collections.Generic;

namespace ConsoleAppDemo
{
    class Program
    {
        static void Main(string[] args)
        {

            IDictionary<int, string> listOfEmployees = new Dictionary<int, string>();
            listOfEmployees.Add(1, "Gwyn");
            listOfEmployees.Add(2, "Joe");
            listOfEmployees.Add(3, "Lora");
            listOfEmployees.Add(4, "Nora");
            listOfEmployees.Add(5, "Peter");

            //Or, we can also create the Dictionary with another way
            /*
            var listOfEmployees = new Dictionary<int, string>()
                {
                    { 1, "Gwyn" },
                    { 2, "Joe" },
                    { 3, "Lora" },
                    { 4, "Nora" },
                    { 5, "Peter" },
                };
            */

            //One way to access the value of the Dictionary collection
            Console.WriteLine(listOfEmployees[1]); //Output: Gwyn

            //Seond way to access the value of the Dictionary collection using the loops
            foreach (KeyValuePair<int, string> employee in listOfEmployees)
            {
                Console.WriteLine(employee.Value);
            }

            //Third way to access the value of the Dictionary collection using the  for loops
            for (int i = 1; i < listOfEmployees.Count; i++)
            {
                Console.WriteLine(listOfEmployees[i]);
            }

            Console.ReadKey();
        }
    }
}
    

The output of both the Foreach and For loops:

Gwyn
Joe
Lora
Nora
Peter

Let's see another example with Employee class.

 
using System;
using System.Collections.Generic;

namespace ConsoleAppDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            //Store some dummy data as an array
            Employee[] listOfEmployees = {
                new Employee(1, "Gwyn", 50, 45),
                new Employee(2, "Joe", 35, 30),
                new Employee(3, "Lora", 25, 25),
                new Employee(4, "Nora", 60, 50),
                new Employee(5, "Peter", 75, 55)
            };


            //One way to access the value of the Dictionary collection
                Console.WriteLine(listOfEmployees[1].Name + " " + listOfEmployees[1].Salary); //Output: Gwyn 86400

            //Seond way to access the value of the Dictionary collection using the loops
            foreach (var employee in listOfEmployees)
            {
                Console.WriteLine(employee.Name + " " + employee.Salary);
            }

            //Third way to access the value of the Dictionary collection using the  for loops
            for (int i = 0; i < listOfEmployees.Length; i++)
            {
                Console.WriteLine(listOfEmployees[i].Name + " " + listOfEmployees[i].Salary);
            }

            Console.ReadKey();
        }
    }

    class Employee
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public float Rate { get; set; }
        public float Salary {
            get {
                return Rate * 8 * 5 * 4 * 12;
            }
        }

        public Employee(int id, string name, int age, float rate)
        {
            this.Id = id;
            this.Name = name;
            this.Age = age;
            this.Rate = rate;
        }
    }
}
    

The output of both the Foreach and For loops:

Gwyn 86400
Joe 57600
Lora 48000
Nora 96000
Peter 105600