Object-Oriented Programming (OOP) is a programming approach in which we model a program using objects (real-world entities). Each object combines:
Why OOP is used:
Core OOP ideas (overview): class, object, encapsulation, inheritance, polymorphism.
A class is a blueprint/template that defines:
An object is an instance of a class. It has actual memory and represents a real entity.
Example idea:
Student (defines roll, name, marks)s1, s2 (real students)Example concept:
balance is data memberdeposit() is member functionEncapsulation means wrapping data and functions together into a single unit (class).
Data hiding is achieved using access specifiers so that internal data is protected.
Typical practice:
This reduces accidental misuse and makes code more reliable.
Access specifiers control who can access class members.
Important Sem-1 understanding:
Two ways:
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Object-Oriented Programming (OOP) is a programming approach in which we model a program using objects (real-world entities). Each object combines:
Why OOP is used:
Core OOP ideas (overview): class, object, encapsulation, inheritance, polymorphism.
A class is a blueprint/template that defines:
An object is an instance of a class. It has actual memory and represents a real entity.
Example idea:
Student (defines roll, name, marks)s1, s2 (real students)Example concept:
balance is data memberdeposit() is member functionEncapsulation means wrapping data and functions together into a single unit (class).
Data hiding is achieved using access specifiers so that internal data is protected.
Typical practice:
This reduces accidental misuse and makes code more reliable.
Access specifiers control who can access class members.
Important Sem-1 understanding:
Two ways:
::Example idea:
int Student::getRoll(){ return roll; }A constructor is a special member function that initializes objects.
Properties:
Why needed:
ClassName(const ClassName &obj)Copy constructor is invoked when:
In exams, write at least two situations.
A destructor is a special member function called automatically when an object is destroyed.
Key points:
~ClassName()Even if we don’t write a destructor, compiler provides a default one.
~.Understanding order is important:
For dynamically created objects:
new → destructor called when delete is usedCreate object → Constructor called → Use object → Scope ends/delete → Destructor called
+------------------+
| Class: Student |
|------------------|
| - roll : int |
| - name : string |
|------------------|
| + setData() |
| + show() |
+------------------+
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From this topic
OOP models programs using objects that combine data and behaviour. Advantages (any three):
Hence OOP helps build maintainable software.
Differences (any three):
A class is a blueprint/template that defines data members (properties) and member functions (behaviour). An object is an instance of a class that has actual memory.
Example:
Student (roll, name, marks)s1, s2 (actual students)Class: Student
- roll
- name
+ show()
Objects: s1, s2
Thus, classes help model real-world entities and objects represent actual entities in memory.