Lesson 30: Banking Practice Program

🎯 Project: Banking Practice Program

Let's build a banking program that practices all the function concepts you've learned! This project combines user-defined functions, return statements, default arguments, and variable scope to create a practical banking simulation.

You'll create functions for checking balance, depositing money, withdrawing money, and displaying account information. This project will help you practice organizing code with functions and managing program state.

Project Requirements

Your banking program should include:

Function to check account balance
Function to deposit money (add to balance)
Function to withdraw money (subtract from balance)
Function to display account information
Use a global variable or function parameters to track balance

Step-by-Step Guide

Here's how to build the banking program:

banking_steps.py
# Step 1: Initialize account balance (global variable)
balance = 1000  # Starting balance

# Step 2: Function to check balance
def check_balance():
    global balance
    return balance

# Step 3: Function to deposit
def deposit(amount):
    global balance
    balance += amount
    return balance

# Step 4: Function to withdraw
def withdraw(amount):
    global balance
    if amount <= balance:
        balance -= amount
        return balance
    else:
        return "Insufficient funds"

# Step 5: Test the functions
print(f"Balance: ${check_balance()}")
deposit(500)
print(f"Balance after deposit: ${check_balance()}")

Complete Banking Program

Here's a complete version with all banking functions:

complete_banking.py
# Banking program with functions
balance = 1000

def check_balance():
    global balance
    return balance

def deposit(amount):
    global balance
    if amount > 0:
        balance += amount
        print(f"Deposited ${amount}. New balance: ${balance}")
        return balance
    else:
        print("Invalid deposit amount")
        return balance

def withdraw(amount):
    global balance
    if amount > balance:
        print("Insufficient funds!")
        return balance
    elif amount <= 0:
        print("Invalid withdrawal amount")
        return balance
    else:
        balance -= amount
        print(f"Withdrew ${amount}. New balance: ${balance}")
        return balance

def display_account():
    print(f"Current Balance: ${check_balance()}")

# Test the banking functions
display_account()
deposit(250)
withdraw(100)
display_account()

Enhanced Features

Add more features to make your banking program more complete:

enhanced_banking.py
# Enhanced banking with transaction history
balance = 1000
transactions = []

def deposit(amount, description="Deposit"):
    global balance, transactions
    if amount > 0:
        balance += amount
        transactions.append(f"{description}: +${amount}")
        print(f"✓ {description}: +${amount}")
    return balance

def withdraw(amount, description="Withdrawal"):
    global balance, transactions
    if amount <= balance and amount > 0:
        balance -= amount
        transactions.append(f"{description}: -${amount}")
        print(f"✓ {description}: -${amount}")
    return balance

def show_transactions():
    print("\nTransaction History:")
    for transaction in transactions:
        print(transaction)
    print(f"\nCurrent Balance: ${balance}")

# Test enhanced features
deposit(500, "Salary")
withdraw(200, "Rent")
show_transactions()

Tips and Best Practices

✅ Function Design Tips

• Use clear, descriptive function names

• Validate inputs (amount > 0, sufficient funds)

• Return useful values from functions

• Use global variables carefully for shared state

• Consider using default arguments for optional parameters

💡 Testing Your Program

Test your banking program with various scenarios: normal deposits/withdrawals, insufficient funds, invalid amounts, and multiple transactions. Make sure the balance updates correctly!

Banking Practice Program