What is the meaning of reference types?

warabe sander

Hi there, it's me again with another dumb question. The gist of my question is if reference types essentially are made of value types, for example an object may contain integers, booleans and chars. So if everything is made up of value types why do reference types exist then?

3 Replies

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Jaish Mathews7y ago
Accepted answer
Before looking into "why do reference types exist?" we should know how they work from background. You also want to know that for variables or objects to work, a Memory location and a Value in that Memory location is needed. Now see below code, which is value type.
int i1 = 100;
int i2 = 200;
2 int type variables defined and here for each variables, system create separate Memory location and also its value allocation. So i1 and i2 has independent Memory locations and Values i.e. 2 each. So 2 times, you created the whole int type.

Now see below code, which is reference type.
public class Book
{
        public string Name { get; set; }
}

Book book1 = new Book() { Name = "Book1 Name" };
Book book2 = new Book() { Name = "Book2 Name" };
Book is a reference type and you created 2 objects of that reference type i.e.book1 and book2. During these Objects creation, no new Memory location would be created and existing Memory location of Book class will be reused. Values only be assigned to existing Memory location of Book class.
So an entire copy of Book class isn't creating during object generation, where entire copy(Memory location + Value) of the value type would be created for value type variables . So reference type support sharing of data and hence gives storage optimization.

What's sharing of data? See below code.
public class Book
{
        public string Name { get; set; }
}

Book book1 = new Book() { Name = "Book1 Name" };
Book book2 = book1;
book2.Name = "Jaish";

Console.WriteLine($"Book1 name is {book1.Name}");
Once running the code, you see as below. We only changed book2 object value, but book1 value also changed with same value. Becasue they shared same memory as of reference types.

So reference types are more related to real world like if you want to mention book "Das Kapital" 100 times, you don't need to describe the whole content in it for 100 times. But just telling the book title "Das Kapital" is enough. Same way, reference types are just using the Memory reference of the Class rather than copying the whole memory each time. Our job is to understand this behaviour and then use them accordingly.
Bidyasagar Mishra7y ago
The Reference type variable is such type of variable in C# that holds the reference of memory address instead of value. class, interface, delegate, array are the reference type. When you create an object of the particular class with new keyword, space is created in the managed heap that holds the reference of classes.

If you are passing reference type variable as parameter, then you will have to use ref keyword with variable.

Example
using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace Reference_Parameter

{

    class Program

    {

        public static void qube(ref int num)

        {

            num = num * num * num;

        }

        static void Main(string[] args)

        {

            int original = 9;

            Console.Write("\ncurrent value of Original is {0}\t", original);

            Program.qube(ref original);

            Console.WriteLine("\nNow the current value of Original is {0}\t", original);

            Console.ReadLine();

        }

    }

}
Elavarasan R7y ago
Hi warabesander,

The programming languages, each type of data (integer, float, and so on) simply reference attribute of data. It tells the cimbiler how the programmer aims to use the data. some languages are do not require data types, automatically convert variable to the type needed for the function.

Advantages:
Flexible work
Improve data quality
Identify reference and domain of values
References:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=2ahUKEwiC_f6BoPfjAhUK7nMBHf8hCW0QFjAEegQIChAQ&url=https%3A%2F%2Fen.m.wikipedia.org%2Fwiki%2FData_type&usg=AOvVaw0xmypJjlM1otJTeLKD-dwu
https://www.quora.com/What-are-the-advantages-of-data-types
https://www.quora.com/Why-data-types-are-required-in-any-programming-language