NOTES OF C++ ACCORDING TO COURSE BOOK.
1. Explain and define classes.
In C++, classes are a fundamental concept of object-oriented programming
(OOP). A class is a blueprint or a template that defines the properties (data
members) and behaviors (member functions) of objects that belong to that
class.
Here's an example of how you can define a class in C++:
```cpp
// Define the class
class Car {
private:
// Private data members (attributes)
std::string color;
std::string make;
std::string model;
int year;
public:
// Public member functions (methods)
// Setter for color
void setColor(const std::string& c) {
color = c;
}
// Getter for color
std::string getColor() const {
return color;
}
// Method to start the car's engine
void startEngine() {
std::cout << "Starting the " << color << " " << make << "'s engine..." <<
std::endl;
// Code to start the engine goes here
}
// Method to accelerate the car
void accelerate(int speed) {
std::cout << "Accelerating the " << color << " " << make << " to " << speed
<< " mph." << std::endl;
// Code to accelerate the car goes here
}
};
```
In this example, the `Car` class has private data members (`color`, `make`,
`model`, and `year`) that represent the attributes of a car object. It also has
public member functions (`setColor`, `getColor`, `startEngine`, and `accelerate`)
that define the behaviors or actions that the car object can perform.
You can create instances of the `Car` class, also known as objects, and access
their attributes and invoke their methods as follows:
```cpp
// Create an instance of the Car class
Car myCar;
// Set the attributes using the setter method
myCar.setColor("Blue");
myCar.make = "Toyota"; // Accessing the member directly (not recommended
for private members)
// Access the attributes using the getter method
std::cout << "My car's color is: " << myCar.getColor() << std::endl;
// Invoke the methods
myCar.startEngine();
myCar.accelerate(60);
```
In C++, classes provide a way to encapsulate data and behavior into a single
unit, making code organization and reusability easier. They also support
concepts like inheritance, polymorphism, and encapsulation, allowing for more
advanced object-oriented programming techniques.
2. Explain about encapsulation in c++.
Encapsulation is an essential principle of object-oriented programming
(OOP) that promotes the concept of bundling data and the operations or
functions that manipulate that data into a single unit called a class. It
enforces the idea of data hiding and provides control over the
accessibility of the class members.
In C++, encapsulation is achieved by using access specifiers: `public`,
`private`, and `protected`. These specifiers define the visibility and
accessibility of the class members.
- Public members: Public members are accessible from anywhere in the
program. They can be accessed by objects of the class or even outside
the class. Public members represent the interface of the class, providing
the external access points to manipulate the object's state and behavior.
- Private members: Private members are only accessible within the class
itself. They are hidden from the external world, allowing the class to
control the access to its internal data and implementation details. Private
members typically encapsulate the internal state of an object and
provide data integrity by preventing direct manipulation from outside
the class.
- Protected members: Protected members are similar to private
members, but they are also accessible within derived classes. They allow
derived classes to access and modify the data and behavior defined in
the base class while still maintaining encapsulation and data hiding.
Encapsulation provides several benefits in C++:
1. Data hiding: By encapsulating data within a class and making it private,
direct access from outside the class is restricted. This ensures that the
data is accessed and modified only through the defined interface (public
methods), which helps maintain data integrity and prevents
unauthorized modifications.
2. Abstraction: Encapsulation allows the class to hide its internal details
and provide a simplified and abstracted interface to the outside world.
The users of the class only need to know how to interact with the public
methods, without worrying about the internal implementation.
3. Modularity and reusability: Encapsulated classes are modular, selfcontained units that can be easily reused in different parts of the
program or in other programs. The internal implementation details are
encapsulated within the class, making it easier to maintain and modify
the code without affecting other parts of the program.
4. Flexibility and maintainability: Encapsulation allows the class to evolve
and change its internal implementation without affecting the code that
uses the class. The external code only relies on the public interface, so
modifications to the internal implementation can be made without
requiring changes to the client code.
Overall, encapsulation in C++ promotes better code organization, data
protection, and code maintainability by providing a clear separation
between the public interface and the private implementation details of a
class.
3. Explain bout objects in c++.
In C++, an object is an instance of a class. It is a concrete representation
of a class that holds its own set of data and can perform actions based
on the defined behaviors (methods) of the class.
When you define a class in C++, you are essentially creating a blueprint
or a template that describes the attributes and behaviors of objects that
belong to that class. However, objects are the actual instances created
from that blueprint, and each object has its own unique set of data.
Here's an example of creating objects in C++:
```cpp
// Define a class called Rectangle
class Rectangle {
private:
double length;
double width;
public:
// Setter methods
void setLength(double l) {
length = l;
}
void setWidth(double w) {
width = w;
}
// Getter methods
double getLength() const {
return length;
}
double getWidth() const {
return width;
}
// Method to calculate the area of the rectangle
double calculateArea() const {
return length * width;
}
};
int main() {
// Create two objects of the Rectangle class
Rectangle rectangle1;
Rectangle rectangle2;
// Set the attributes of the first rectangle
rectangle1.setLength(5.0);
rectangle1.setWidth(3.0);
// Set the attributes of the second rectangle
rectangle2.setLength(7.0);
rectangle2.setWidth(4.0);
// Calculate and display the area of each rectangle
double area1 = rectangle1.calculateArea();
double area2 = rectangle2.calculateArea();
cout << "Area of rectangle 1: " << area1 << endl;
cout << "Area of rectangle 2: " << area2 << endl;
return 0;
}
```
In this example, the `Rectangle` class represents a blueprint for
rectangles. In the `main` function, two objects (`rectangle1` and
`rectangle2`) of the `Rectangle` class are created using the default
constructor. Each object has its own separate attributes (`length` and
`width`).
You can then use the object's methods to set the values of the attributes
and invoke other behaviors defined in the class. In this case, the
`setLength` and `setWidth` methods are used to set the attributes of
each rectangle. The `calculateArea` method is invoked to calculate the
area of each rectangle.
Objects allow you to work with specific instances of a class, storing and
manipulating their data, and invoking their behaviors. Each object
maintains its own state and can interact with other objects and the
program as a whole.
4. Member functions in c++.
Member functions in C++ are functions that are declared and defined
inside a class. They are also referred to as methods or member methods.
Member functions operate on the data members of the class and can be
used to perform actions, manipulate the data, or provide services related
to the class.
There are two types of member functions in C++: instance member
functions and static member functions.
1. Instance Member Functions:
- Instance member functions are associated with specific objects or
instances of a class.
- They have access to the data members and other member functions
of the class.
- They are invoked using an object or instance of the class.
- Inside an instance member function, the keyword `this` can be used
to refer to the current object.
Here's an example demonstrating instance member functions:
```cpp
class Circle {
private:
double radius;
public:
// Setter method for radius
void setRadius(double r) {
radius = r;
}
// Getter method for radius
double getRadius() const {
return radius;
}
// Member function to calculate the area
double calculateArea() const {
return 3.14159 * radius * radius;
}
};
int main() {
// Create an object of the Circle class
Circle myCircle;
// Set the radius of the circle
myCircle.setRadius(5.0);
// Get the radius and calculate the area
double radius = myCircle.getRadius();
double area = myCircle.calculateArea();
cout << "Radius: " << radius << endl;
cout << "Area: " << area << endl;
return 0;
}
```
In this example, the `Circle` class has instance member functions
`setRadius`, `getRadius`, and `calculateArea`. These member functions
are invoked on an object (`myCircle`) to set the radius, get the radius
value, and calculate the area of the circle.
2. Static Member Functions:
- Static member functions are associated with the class itself rather
than with instances of the class.
- They don't have access to the instance-specific data members, as they
are not bound to any specific object.
- They can only access static data members and other static member
functions of the class.
- They are invoked using the class name followed by the scope
resolution operator `::`.
Here's an example demonstrating static member functions:
```cpp
class MathUtils {
public:
// Static member function to calculate the square of a number
static int square(int num) {
return num * num;
}
};
int main() {
int result = MathUtils::square(5);
cout << "Square: " << result << endl;
return 0;
}
```
In this example, the `MathUtils` class has a static member function
`square` that calculates the square of a number. The static member
function is invoked using the class name (`MathUtils`) followed by the
scope resolution operator (`::`).
Static member functions are often used for utility functions or operations
that don't require access to instance-specific data. They can be accessed
without creating an object of the class.
Member functions in C++ provide the behavior and functionality
associated with a class. They allow objects of the class to perform
actions, manipulate data, and provide services based on the defined
operations.
5. Nesting member functions in c++.
In C++, nesting member functions refers to the concept of defining a
member function inside another member function of the same class.
This allows the nested function to access the data members and other
member functions of the enclosing class.
Here's an example to demonstrate nesting member functions in C++:
```cpp
class OuterClass {
private:
int outerData;
public:
void outerFunction() {
outerData = 10;
// Nested member function
void nestedFunction() {
int nestedData = 20;
int result = outerData + nestedData;
cout << "Result: " << result << endl;
}
nestedFunction();
}
};
int main() {
OuterClass obj;
obj.outerFunction();
return 0;
}
```
In this example, the `OuterClass` has an outer member function called
`outerFunction`. Inside this function, we define a nested member
function called `nestedFunction`. The nested function can access the
`outerData` member variable of the enclosing class and perform
calculations.
When the `outerFunction` is called on an instance of `OuterClass`, it sets
the value of `outerData` and invokes the nested function
`nestedFunction`. The nested function then performs the addition of
`outerData` and its own `nestedData` and displays the result.
It's important to note that nested member functions can only be called
from within their enclosing function. They are not directly accessible
outside the enclosing function or from other member functions of the
class.
Nesting member functions can be useful in situations where you have
complex logic or sub-tasks that are specific to a particular member
function and don't need to be accessed from other parts of the class.
They provide a way to encapsulate related functionality within a single
member function.
6. Passing objects as arguments in c++.
In C++, objects can be passed as arguments to functions just like any
other data type. When passing an object as an argument, you can either
pass it by value or by reference.
1. Passing Objects by Value:
- When an object is passed by value, a copy of the object is created and
passed to the function.
- The function works with the copy of the object, and any modifications
made to the object inside the function will not affect the original object.
- Passing objects by value can be useful when you want to work with a
local copy of the object without modifying the original object.
Here's an example:
```cpp
class Point {
private:
int x;
int y;
public:
Point(int xVal, int yVal) : x(xVal), y(yVal) {}
// Getter methods
int getX() const {
return x;
}
int getY() const {
return y;
}
};
// Function that takes an object by value
void displayPoint(Point point) {
cout << "X: " << point.getX() << ", Y: " << point.getY() << endl;
}
int main() {
Point p(3, 4);
displayPoint(p);
return 0;
}
```
In this example, the `displayPoint` function takes a `Point` object by
value. Inside the function, a copy of the `Point` object is created, and its
coordinates are displayed. The original object remains unchanged.
2. Passing Objects by Reference:
- When an object is passed by reference, the function receives a
reference to the original object.
- Any modifications made to the object inside the function will directly
affect the original object.
- Passing objects by reference can be useful when you want to modify
the original object or avoid the overhead of creating a copy.
Here's an example:
```cpp
class Point {
private:
int x;
int y;
public:
Point(int xVal, int yVal) : x(xVal), y(yVal) {}
// Getter methods
int getX() const {
return x;
}
int getY() const {
return y;
}
// Setter methods
void setX(int xVal) {
x = xVal;
}
void setY(int yVal) {
y = yVal;
}
};
// Function that takes an object by reference
void movePoint(Point& point, int deltaX, int deltaY) {
int newX = point.getX() + deltaX;
int newY = point.getY() + deltaY;
point.setX(newX);
point.setY(newY);
}
int main() {
Point p(3, 4);
movePoint(p, 2, 3);
cout << "New X: " << p.getX() << ", New Y: " << p.getY() << endl;
return 0;
}
```
In this example, the `movePoint` function takes a `Point` object by
reference. Inside the function, the coordinates of the object are modified
by adding the specified `deltaX` and `deltaY` values. The modifications
made to the object are reflected in the original object.
Passing objects by reference is generally preferred when you want to
modify the original object or when the object is large and you want to
avoid the overhead of copying the entire object.
By passing objects as arguments to functions, you can operate on the
data within the object and perform various operations or modifications
based on the requirements of your program.
7. Explain friend function in c++.
In C++, a friend function is a function that is granted access to the private
and protected members of a class. It is declared inside the class, but it is
not a member function of that class. Friend functions can be either
regular functions or other class methods declared as friend.
Here are some key points about friend functions:
1. Access to Private and Protected Members: Friend functions have the
ability to access and modify the private and protected members of a
class, even though they are not members of the class itself. This allows
them to bypass the usual access restrictions.
2. Declaration Inside the Class: Friend functions are declared inside the
class that grants them friendship. They are usually declared in the class
definition, but the actual implementation is done outside the class body.
3. No "this" Pointer: Friend functions do not have a "this" pointer, as they
are not members of any specific object. This means they cannot access
the object's non-static members directly.
4. Not Inherited: Friend functions are not inherited by derived classes. If
a class is derived from another class, the derived class does not inherit
the friend functions of the base class.
Here's an example to illustrate the usage of a friend function:
```cpp
class MyClass {
private:
int privateData;
public:
MyClass(int data) : privateData(data) {}
friend void friendFunction(MyClass& obj);
};
void friendFunction(MyClass& obj) {
obj.privateData += 10;
cout << "Friend Function: " << obj.privateData << endl;
}
int main() {
MyClass myObj(5);
friendFunction(myObj);
return 0;
}
```
In this example, the `friendFunction` is declared as a friend of the
`MyClass` class. It can access the private member `privateData` of the
`MyClass` objects. In the `main` function, the `friendFunction` is called
on a `MyClass` object, allowing it to modify the private member.
Friend functions are useful in scenarios where external functions or
other class methods need to work closely with a class and require access
to its private members. They provide a way to extend the access
privileges beyond the class itself without making those members public.
However, it is generally recommended to use friend functions sparingly
and adhere to the principles of encapsulation as much as possible.
8. Explain about static member function in c++.
In C++, a static member function is a member function that belongs to
the class rather than to the individual objects of the class. It is associated
with the class itself rather than with any specific instance of the class.
Therefore, it can be called directly using the class name without creating
an object of the class.
Here are some important characteristics of static member functions:
1. Belongs to the Class: Static member functions are defined within the
class definition and are declared using the `static` keyword. They are not
associated with any specific object or instance of the class.
2. No Access to Instance-specific Data: Static member functions do not
have access to the non-static (instance-specific) data members of the
class. They can only access static data members and other static member
functions.
3. Invoked using Class Name: Static member functions can be called
using the class name followed by the scope resolution operator (`::`).
They can also be called using an object of the class, but it is not
necessary to create an object to invoke a static member function.
4. Independent of Objects: Static member functions do not operate on
individual objects but rather on the class as a whole. They are
independent of any specific object's state and can be used to perform
operations or provide services that are not tied to a particular instance.
5. Accessible without Object Creation: Since static member functions are
not tied to specific objects, they can be accessed without creating an
object of the class. This can be useful for utility functions or operations
that don't require object-specific data.
Here's an example to illustrate the usage of static member functions:
```cpp
class MathUtils {
private:
static const double PI;
public:
static double calculateCircleArea(double radius) {
return PI * radius * radius;
}
};
const double MathUtils::PI = 3.14159;
int main() {
double area = MathUtils::calculateCircleArea(5.0);
cout << "Area: " << area << endl;
return 0;
}
```
In this example, the `MathUtils` class has a static member function
`calculateCircleArea` that calculates the area of a circle given its radius.
The static member function is defined with the `static` keyword and can
be invoked directly using the class name
(`MathUtils::calculateCircleArea`). It does not require an object of the
class to be created.
Static member functions are commonly used for operations that are not
dependent on the state of a specific object or for utility functions that do
not require access to instance-specific data. They provide a way to
organize and group related functionality at the class level rather than the
instance level.
Completed chapter 3.