Introduction

Object Oriented Programming in one of the most important concepts in terms of building scalable softwares.As python is also a object oriented programming language we should get fimiliar to the OOP terminologies by building programs.

In this repository we will build basic programs using Object oriented programming in Python which will mainly focus on implementing Object oriented programming concepts.

Concepts

• Magic method
• Constructor (Will be added soon)
• Self object (Will be added soon)

Magic Method

• Dunder or Magic methods in Python are the methods having two prefixes and suffix underscores in the method name.
• Dunder here means “Double Under (Underscores)”. These are commonly used for operator overloading.
• You will get to know more by clicking here.

Programs

We will be building following programs

• Atm Banking System

  • Our Atm Banking System will have the following features
    • Select Bank
      • User will be able to select bank
    • Select option from Menu
      • User will be able to select operations from the menu
    • Create Pin
      • User has to create pin in order to operate
    • Check Pin
      • Entered pin will be checked after creating pin
    • Deposit Money
      • User will be able to deposit money
    • Withdraw Money
      • User will be able to withdraw money
    • Check Balance
      • User will be able to check balance

• Custom Datatype (It will be added soon)

  • We will create a custom datatype named fraction which will have the following functionalities
    • Addition
      • Add two fractions
    • Subtraction
      • Subtract two fractions
    • Multiplication
      • Multiply two fractions
    • Division
      • Divide two fractions

All the features mentioned above will be implemented using OOP as said before.

Usage of OOP

• User will be able to transit between multiple banks at the same time which will have different pin codes, balance etc.

Atm Banking System

Atm is a very widely used banking system in today's world which has basic features like depositing money, withdrawing money, Checking balance etc. Our Atm will also have features like these.

• The features are mentioned below

Select Bank

• User will have to select a bank from the given options and then the menu method will be called by the object.

• The options will be:

  0 . Exit

  1 . Asia Bank

  2 . Prime Bank

Code

def main():
    asiaBank = Atm()
    primeBank = Atm()

    while 1:
        choice = int(input("""Please Select your bank
        0. Exit
        
        1. Asia Bank: 
        2. Prime Bank
        """))

        if choice == 1:
            print(f"Thanks for choosing Asia Bank")
            while 1:
                stay = asiaBank.menu()
                if not stay:
                    break
        elif choice == 2:
            print(f"Thanks for choosing Prime Bank")
            while 1:
                stay = primeBank.menu()
                if not stay:
                    break
        elif choice == 0:
            break
        else:
            print("Please enter a valid choice")


main()

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Select from Menu

• User will have to select an operation from the menu.

• The options will be similiar to the following:

  • Enter 0 to exit
  • Enter 1 to create pin
  • Enter 2 to deposit
  • Enter 3 to withdraw
  • Enter 4 to check balance

Code

def menu(self):
        user_input = int(input("""
                        0. Enter 0 to exit
                        1. Enter 1 to create pin
                        2. Enter 2 to deposit
                        3. Enter 3 to withdraw
                        4. Enter 4 to check balance
        """))

        if user_input == 1:
            self.create_pin()
        elif user_input == 2:
            self.deposit()
        elif user_input == 3:
            self.withdraw()
        elif user_input == 4:
            self.check_balance()
        elif user_input < 0 or user_input > 4:
            print("Please Enter a valid input")

        return user_input

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Create Pin

• We will be creating pins for every object and pin is required to perform all other operations.
• Without a pin no one can perform any other operation.
• If pin is created then every time someone is going to perform any operation pin will be checked.

Code

def __init__(self):
        self.pin = ""
        self.balance = 0

def create_pin(self):
        if self.pin == "":
            self.pin = input("Create you pin please: ")
            print("Your pin has been set successfully")
        else:
            print("There is already a pin")

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Check Pin

• If there is a pin already existing in the program then we will check the pin everytime before performing any operation.

Code

    def check_pin(self):
        pin = input("Enter your pin please: ")
        if pin == self.pin:
            return 1
        else:
            return 0

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Deposit Money

• In order to deposit money user has to have a pin.
• If he doesn't have a pin he has to create one and if he has then we will check the pin he has entered.
• After entering the right pin his entered amount will be added to the balance.

Code

    def deposit(self):
        if self.pin == "":
            self.create_pin()

        if self.check_pin():
            amount = input("Please enter your deposit amount: ")
            self.balance += int(amount)
            print("Amount has been deposited successfully")
        else:
            print("You have entered wrong pin, please re-enter your pin")
            self.deposit()

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Withdraw Money

• Just like deposit method, withdraw method will also be performed after entering the right pin.
• In this case user has to enter a valid amount as well.
• If the entered amount is sufficient then he can withdraw money otherwise he will be again asked to enter a sufficient amount.

Code

def withdraw(self):
        if self.pin == "":
            self.create_pin()
        if self.check_pin():
            amount = int(input("Please enter your withdrawal amount or press 0 to return to menu: "))
            if amount == 0:
                pass
            elif amount < 0:
                print("Invalid amount")
            elif self.balance >= amount:
                self.balance -= amount
                print("Amount has been withdrawn successfully")
            else:
                print("Insufficient balance")
                self.withdraw()
        else:
            print("You have entered wrong pin")
            self.withdraw()

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Check Balance

• User must create a pin and enter the correct pin in order to check balance.
• User will be shown balance when he enters the correct pin just like all the above-mentioned methods.

Code

    def check_balance(self):
        if self.pin == "":
            self.create_pin()
        if self.check_pin():
            print(f"Your current balance is : {self.balance}")
        else:
            print("You have entered wrong pin")
            self.check_balance()

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