📢 Updated and refinded at : 21-feb-2025
Bundling the data member and member function into a single unit is called encapsulation. Remember the term “capsule”. We put all the medicine inside a wrapper and call it capsule. Similarly, wrap the data members and member functions together is called encapsulation.
Now we need to understand few terms.
- Data members : Attributes or properties (eg. name, age)
- Member functions: Methods (PrintDetails)
👉 We wrap up the data members (attributes or properties) and member functions (methods) into a single unit (class).
📺 Other OOPs Related articles
Let’s understand Encapsulation with an example.
public class Student
{
public string name;
public int age;
public void PrintDetails()
{
Console.WriteLine($"Name: {name}, Age: {age}");
}
}
👉 In this example, we are bundling the data members (name, age) and member functions (PrintDetails) into a single unit (Student).
Now we can use the Student class, by instantiating it.
public class Program
{
static void Main()
{
Student student = new();
student.name= "John Doe ";
student.age = 12;
student.PrintDetails();
}
}
That is all you need to know about encapsulation. If you want to know more about it like it’s benefits, then you can read further, otherwise you can skip it.
Benefits of Encapsulation
1. Data Hiding
Encapsulation helps you to hide your sensitive data from the end user.
Why data hiding? 😕
In the previous example, Student have two public attributes (name and age). These two attributes are not secure.
- Name: User can enter the name with any length. There is no restriction. What if he enters 2000 character long name.
- Age: What if user enters the age in negative numbers or 0.
So, you need some kind of restrictions in that data.
---
title: Data hiding, to validate `_name` and `_age`, we are hiding `_name` and `_age` from users.
---
classDiagram
class Student{
-string name
-int age
+SetName(string)
+GetName() string
+SetAge(int)
+GetName() int
}
Let’s see how we can do it in c#.
public class Student
{
private string? _name;
private int _age;
public void SetName(string name)
{
if (!string.IsNullOrWhiteSpace(name) && name.Length <= 30)
{
_name = name;
}
else throw new Exception("Invalid Name.Name's length must between 0 and 31");
}
public string GetName()=> _name;
public void SetAge(int age)
{
if (age>0)
{
_age=age;
}
else throw new Exception("Invalid Age.Age should be greater than 0");
}
public int GetAge() => _age;
}
public class Program
{
static void Main()
{
Student student = new();
student.SetName("John Doe");
student.SetAge(10);
Console.WriteLine($"Name: {student.GetName()}, Age: {student.GetAge()}");
}
}
We declares the name and age as private and setting/getting them through the public methods.
👉 You can achieve same with properties. It is the modern approach of validating data.
public class Student
{
private string name;
private int age;
public string Name
{
get => name;
set
{
if (!string.IsNullOrWhiteSpace(value) && value.Length <= 30)
{
name = value;
}
else throw new Exception("Invalid Name.Name's length must between 0 and 31");
}
}
public int Age
{
get => age;
set
{
if (value > 0)
{
age = value;
}
else
throw new Exception("Invalid Age.Age should be greater than 0");
}
}
}
public class Program
{
static void Main()
{
Student student = new();
student.Name="John Doe";
student.Age=12;
Console.WriteLine($"Name: {student.Name}, Age: {student.Age}");
}
}
2. Access modifiers
You can set the protection level for your properties and methods with access modifiers like private, protected, internal etc.
3. Read-only data
Some time you want the readonly data in your class.
public string MyProperty { get; }
Summary
- Wrapping up data into a single unit is called encapsulation.
- Encapsulation helps to achieve
data hiding, that helps us to set the validation rules for our data members or fields. - Encapsulation also helps us to define readonly members.
Original post by Ravindra Devrani on January 31, 2024. Updated and refinded at : 21-feb-2025.