Topic: Python Create New Class Rectangle

Write a Python Program to perform the above mentioned OOP concepts. The Rectangle class will have:

- Two instance variables: length and width
- Two instance methods:
- compute_area() and compute_perimeter()
- The formula of area of rectangle is to multiply length of rectangle by the width of the rectangle.
- Similarly, the formula of perimeter of the rectangle is adding all four sides of the rectangle. Therefore perimeter=L+L+W+W
- That is perimeter = 2L + 2W
- And so, perimeter = 2(L+W)
- Moreover the Rectanggle class will have a parameterized constructor to initialize the instance variables of the object.

### What is the Formula to Calculate Area of Rectangle?

area = length x width

### What is the formula to Compute Perimeter of Rectangle?

perimeter = 2 (length+width)

## Python Source Code Python Create New Class Rectangle

# Write a Python Program using OOP - class and objects # create a class Rectangle to provide the functionality # of finding area and perimeter of rectangle objects with # instance vaiables: length and width # constructor # computer_area() method # computer_perimeter() method # www.easycodebook.com # define a class Rectangle class Rectangle: # define a constructor def __init__(self, length, width): self.length = length self.width = width # define an instance method to calculate area of rectangle def compute_area(self): return self.length * self.width # define an instance method to calculate perimeter of rectangle def compute_perimeter(self): return 2 * (self.length+self.width) # end of the class # get input from the user l= float(input('Please Enter the Length of the Rectangle: ')) w= float(input('Please Enter the Width of the Rectangle: ')) # create first object object1 = Rectangle(l,w) # call methods of rectangle area = object1.compute_area() perimeter = object1.compute_perimeter() # print area and perimeter of the rectangle object print("Area of Rectangle object = %.2f" %area) print("Perimeter of Rectangle object= %.2f" %perimeter)

### How to Define a Rectangle Class in Python

First of all use class keyword to define a Rectangle class:

class Rectangle:

### Define a constructor in Rectangle Class

```
def __init__(self, length, width):
self.length = length
self.width = width
```

### Define compute_area() method

```
def computer_area(self):
return self.length * self.width
```

### Define compute_perimeter() method

```
def computer_perimeter(self):
return 2*(self.length + self.width)
```

### Get Input from the User at Runtime

```
l= float(input('Please Enter the Length of the Rectangle: '))
w= float(input('Please Enter the Width of the Rectangle: '))
```

### Create an Object of Rectangle Class

```
obj = Rectangle(l,w)
```

### Call the compute_area() method for Object of Rectangle Class

```
USing dot notation with object.method() syntax to call the method
compute_area() method to calculate area of the rectangle object.
And the returned value will be stored in area variable
area = obj.compute_area()
```

### Call the compute_perimeter() method for Object of Rectangle Class

```
USe dot notation with object.method() syntax to call the method
compute_perimeter()
And the returned value will be stored in perimeter variable
perimeter = obj.compute_perimeter()
```

### Show Results area and perimeter for Object of Rectangle Class

```
Here we will use print() function to print the details
like area and perimeter of the rectangle object on the screen.
We will use %.2f to round the value upto 2 decimal places.
print("Area of Rectangle object = %.2f" %area)
print("Perimeter of Rectangle object= %.2f" %perimeter)
```

## Second version of Rectangle Class Program

class Rectangle(): ''' Rectangle class Program''' # constructor def __init__(self,breadth,length): self.breadth=breadth self.length=length # calculate_area( ) method def calculate_area(self): return self.breadth*self.length # get input from the user for length and breadth length=int(input("Enter length of rectangle: ")) breadth=int(input("Enter breadth of rectangle: ")) # create new Rectangle object with input values rec1=Rectangle(length,breadth) # call calculate_area() method and print result print("Area of rectangle:",rec1.calculate_area())

OUTPUT: Enter length of rectangle: 5 Enter breadth of rectangle: 10 Area of rectangle: 50 Another Sample Run of the Program Enter length of rectangle: 7 Enter breadth of rectangle: 11 Area of rectangle: 77

## Third Version of Rectangle Class Program

class Rectangle: # constructor for Initialization def __init__(self): # The only members are length and width self.length = 1 self.width = 1 # Write Setters methods for width and length def set_width(self, width): self.width = width def set_length(self, length): self.length = length # Write Getters methods for the both instance variables def get_width(self): return self.width def get_length(self): return self.length # find area method def find_area(self): return self.length * self.width # show String representation of object def __str__(self): return 'length = {}, width = {}'.format(self.length, self.width) rectangle1 = Rectangle() # set width and length of rectangle1 object rectangle1.set_width(7) rectangle1.set_length(4) # call find_area( ) method ar = rectangle1.find_area(); # display values of instance variables of rectangle1 object print(rectangle1) # show area of rectangle1 object print("Area = ",ar)

OUTPUT: length = 4, width = 7 Area = 28

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