{"title":"Exercise: Classes and Objects","description":null,"content":"Try implementing the below code exercises to reinforce your understanding. Your goal is to implement the classes below so that they produce the expected output.\n\n---\n\n# Exercise 1: Bank Account\n\n\n**Problem:** Create a `BankAccount` class that manages a simple bank account with deposit, withdrawal, and balance checking functionality.\n\n**Requirements:**\n\n- Fields: `accountNumber`, `ownerName`, `balance`\n- Constructor that initializes the account with owner name and account number (balance starts at 0)\n- `deposit(amount)`: adds money to balance (only positive amounts)\n- `withdraw(amount)`: removes money if sufficient balance exists, returns success/failure\n- `getBalance()`: returns current balance\n\n```java\nclass BankAccount {\n // Add private fields: accountNumber (String), ownerName (String), balance (double)\n\n public BankAccount(String accountNumber, String ownerName) {\n // Initialize fields. Balance should start at 0.\n }\n\n public void deposit(double amount) {\n // Add amount to balance (only if amount is positive)\n }\n\n public boolean withdraw(double amount) {\n // Remove amount from balance if sufficient funds exist\n // Return true if successful, false otherwise\n return false;\n }\n\n public double getBalance() {\n // Return the current balance\n return 0;\n }\n}\n\n// Test your implementation\npublic class Main {\n public static void main(String[] args) {\n BankAccount account = new BankAccount(\"123456\", \"John Doe\");\n account.deposit(1000);\n System.out.println(account.getBalance()); // Should print 1000.0\n\n boolean success = account.withdraw(500);\n System.out.println(success); // Should print true\n System.out.println(account.getBalance()); // Should print 500.0\n\n success = account.withdraw(1000);\n System.out.println(success); // Should print false\n }\n}\n```\n\n```python\nclass BankAccount:\n def __init__(self, account_number: str, owner_name: str):\n # Initialize fields: account_number, owner_name, balance (starts at 0)\n pass\n\n def deposit(self, amount: float) -> None:\n # Add amount to balance (only if amount is positive)\n pass\n\n def withdraw(self, amount: float) -> bool:\n # Remove amount from balance if sufficient funds exist\n # Return True if successful, False otherwise\n return False\n\n def get_balance(self) -> float:\n # Return the current balance\n return 0\n\nif __name__ == \"__main__\":\n account = BankAccount(\"123456\", \"John Doe\")\n account.deposit(1000)\n print(account.get_balance()) # Should print 1000.0\n\n success = account.withdraw(500)\n print(str(success).lower()) # Should print true\n print(account.get_balance()) # Should print 500.0\n\n success = account.withdraw(1000)\n print(str(success).lower()) # Should print false\n```\n\n```cpp\n#include \n#include \n#include \nusing namespace std;\n\nclass BankAccount {\nprivate:\n // Add private fields: accountNumber (string), ownerName (string), balance (double)\n\npublic:\n BankAccount(const string& accountNumber, const string& ownerName) {\n // Initialize fields. Balance should start at 0.\n }\n\n void deposit(double amount) {\n // Add amount to balance (only if amount is positive)\n }\n\n bool withdraw(double amount) {\n // Remove amount from balance if sufficient funds exist\n // Return true if successful, false otherwise\n return false;\n }\n\n double getBalance() const {\n // Return the current balance\n return 0;\n }\n};\n\nint main() {\n BankAccount account(\"123456\", \"John Doe\");\n account.deposit(1000);\n cout << fixed << setprecision(1) << account.getBalance() << endl; // Should print 1000.0\n\n bool success = account.withdraw(500);\n cout << boolalpha << success << endl; // Should print true\n cout << fixed << setprecision(1) << account.getBalance() << endl; // Should print 500.0\n\n success = account.withdraw(1000);\n cout << boolalpha << success << endl; // Should print false\n\n return 0;\n}\n```\n\n```go\npackage main\n\nimport \"fmt\"\n\ntype BankAccount struct {\n\t// Add private fields: accountNumber (string), ownerName (string), balance (float64)\n}\n\nfunc NewBankAccount(accountNumber string, ownerName string) *BankAccount {\n\t// Initialize fields. Balance should start at 0.\n\treturn &BankAccount{}\n}\n\nfunc (b *BankAccount) Deposit(amount float64) {\n\t// Add amount to balance (only if amount is positive)\n}\n\nfunc (b *BankAccount) Withdraw(amount float64) bool {\n\t// Remove amount from balance if sufficient funds exist\n\t// Return true if successful, false otherwise\n\treturn false\n}\n\nfunc (b *BankAccount) GetBalance() float64 {\n\t// Return the current balance\n\treturn 0\n}\n\n// Test your implementation\nfunc main() {\n\taccount := NewBankAccount(\"123456\", \"John Doe\")\n\taccount.Deposit(1000)\n\tfmt.Printf(\"%.1f\\n\", account.GetBalance()) // Should print 1000.0\n\n\tsuccess := account.Withdraw(500)\n\tfmt.Println(success) // Should print true\n\tfmt.Printf(\"%.1f\\n\", account.GetBalance()) // Should print 500.0\n\n\tsuccess = account.Withdraw(1000)\n\tfmt.Println(success) // Should print false\n}\n```\n\n```csharp\nusing System;\n\npublic class BankAccount\n{\n // Add private fields: _accountNumber (string), _ownerName (string), _balance (double)\n\n public BankAccount(string accountNumber, string ownerName)\n {\n // Initialize fields. Balance should start at 0.\n }\n\n public void Deposit(double amount)\n {\n // Add amount to balance (only if amount is positive)\n }\n\n public bool Withdraw(double amount)\n {\n // Remove amount from balance if sufficient funds exist\n // Return true if successful, false otherwise\n return false;\n }\n\n public double GetBalance()\n {\n // Return the current balance\n return 0;\n }\n}\n\npublic class Program\n{\n public static void Main()\n {\n var account = new BankAccount(\"123456\", \"John Doe\");\n account.Deposit(1000);\n Console.WriteLine($\"{account.GetBalance():F1}\"); // Should print 1000.0\n\n bool success = account.Withdraw(500);\n Console.WriteLine(success.ToString().ToLower()); // Should print true\n Console.WriteLine($\"{account.GetBalance():F1}\"); // Should print 500.0\n\n success = account.Withdraw(1000);\n Console.WriteLine(success.ToString().ToLower()); // Should print false\n }\n}\n```\n\n```typescript\nclass BankAccount {\n // Add private fields: accountNumber (string), ownerName (string), balance (number)\n\n constructor(accountNumber: string, ownerName: string) {\n // Initialize fields. Balance should start at 0.\n }\n\n deposit(amount: number): void {\n // Add amount to balance (only if amount is positive)\n }\n\n withdraw(amount: number): boolean {\n // Remove amount from balance if sufficient funds exist\n // Return true if successful, false otherwise\n return false;\n }\n\n getBalance(): number {\n // Return the current balance\n return 0;\n }\n}\n\n// Test your implementation\nconst account = new BankAccount(\"123456\", \"John Doe\");\naccount.deposit(1000);\nconsole.log(account.getBalance().toFixed(1)); // Should print 1000.0\n\nlet success = account.withdraw(500);\nconsole.log(success); // Should print true\nconsole.log(account.getBalance().toFixed(1)); // Should print 500.0\n\nsuccess = account.withdraw(1000);\nconsole.log(success); // Should print false\n```\n\n#### Solutions\n\n```java\nclass BankAccount {\n private String accountNumber;\n private String ownerName;\n private double balance;\n\n public BankAccount(String accountNumber, String ownerName) {\n this.accountNumber = accountNumber;\n this.ownerName = ownerName;\n this.balance = 0;\n }\n\n public void deposit(double amount) {\n if (amount > 0) {\n balance += amount;\n }\n }\n\n public boolean withdraw(double amount) {\n if (amount > 0 && balance >= amount) {\n balance -= amount;\n return true;\n }\n return false;\n }\n\n public double getBalance() {\n return balance;\n }\n}\n\npublic class Main {\n public static void main(String[] args) {\n BankAccount account = new BankAccount(\"123456\", \"John Doe\");\n account.deposit(1000);\n System.out.println(account.getBalance());\n\n boolean success = account.withdraw(500);\n System.out.println(success);\n System.out.println(account.getBalance());\n\n success = account.withdraw(1000);\n System.out.println(success);\n }\n}\n```\n\n```python\nclass BankAccount:\n def __init__(self, account_number: str, owner_name: str):\n self._account_number = account_number\n self._owner_name = owner_name\n self._balance = 0.0\n\n def deposit(self, amount: float) -> None:\n if amount > 0:\n self._balance += amount\n\n def withdraw(self, amount: float) -> bool:\n if amount > 0 and self._balance >= amount:\n self._balance -= amount\n return True\n return False\n\n def get_balance(self) -> float:\n return self._balance\n\nif __name__ == \"__main__\":\n account = BankAccount(\"123456\", \"John Doe\")\n account.deposit(1000)\n print(account.get_balance())\n\n success = account.withdraw(500)\n print(str(success).lower())\n print(account.get_balance())\n\n success = account.withdraw(1000)\n print(str(success).lower())\n```\n\n```cpp\n#include \n#include \n#include \nusing namespace std;\n\nclass BankAccount {\nprivate:\n string accountNumber;\n string ownerName;\n double balance;\n\npublic:\n BankAccount(const string& accountNumber, const string& ownerName)\n : accountNumber(accountNumber), ownerName(ownerName), balance(0) {}\n\n void deposit(double amount) {\n if (amount > 0) {\n balance += amount;\n }\n }\n\n bool withdraw(double amount) {\n if (amount > 0 && balance >= amount) {\n balance -= amount;\n return true;\n }\n return false;\n }\n\n double getBalance() const {\n return balance;\n }\n};\n\nint main() {\n BankAccount account(\"123456\", \"John Doe\");\n account.deposit(1000);\n cout << fixed << setprecision(1) << account.getBalance() << endl;\n\n bool success = account.withdraw(500);\n cout << boolalpha << success << endl;\n cout << fixed << setprecision(1) << account.getBalance() << endl;\n\n success = account.withdraw(1000);\n cout << boolalpha << success << endl;\n\n return 0;\n}\n```\n\n```go\npackage main\n\nimport \"fmt\"\n\ntype BankAccount struct {\n\taccountNumber string\n\townerName string\n\tbalance float64\n}\n\nfunc NewBankAccount(accountNumber, ownerName string) *BankAccount {\n\treturn &BankAccount{\n\t\taccountNumber: accountNumber,\n\t\townerName: ownerName,\n\t\tbalance: 0,\n\t}\n}\n\nfunc (b *BankAccount) Deposit(amount float64) {\n\tif amount > 0 {\n\t\tb.balance += amount\n\t}\n}\n\nfunc (b *BankAccount) Withdraw(amount float64) bool {\n\tif amount > 0 && b.balance >= amount {\n\t\tb.balance -= amount\n\t\treturn true\n\t}\n\treturn false\n}\n\nfunc (b *BankAccount) GetBalance() float64 {\n\treturn b.balance\n}\n\nfunc main() {\n\taccount := NewBankAccount(\"123456\", \"John Doe\")\n\taccount.Deposit(1000)\n\tfmt.Printf(\"%.1f\\n\", account.GetBalance())\n\n\tsuccess := account.Withdraw(500)\n\tfmt.Println(success)\n\tfmt.Printf(\"%.1f\\n\", account.GetBalance())\n\n\tsuccess = account.Withdraw(1000)\n\tfmt.Println(success)\n}\n```\n\n```csharp\nusing System;\n\npublic class BankAccount\n{\n private string _accountNumber;\n private string _ownerName;\n private double _balance;\n\n public BankAccount(string accountNumber, string ownerName)\n {\n _accountNumber = accountNumber;\n _ownerName = ownerName;\n _balance = 0;\n }\n\n public void Deposit(double amount)\n {\n if (amount > 0)\n {\n _balance += amount;\n }\n }\n\n public bool Withdraw(double amount)\n {\n if (amount > 0 && _balance >= amount)\n {\n _balance -= amount;\n return true;\n }\n return false;\n }\n\n public double GetBalance()\n {\n return _balance;\n }\n}\n\npublic class Program\n{\n public static void Main()\n {\n var account = new BankAccount(\"123456\", \"John Doe\");\n account.Deposit(1000);\n Console.WriteLine($\"{account.GetBalance():F1}\");\n\n bool success = account.Withdraw(500);\n Console.WriteLine(success.ToString().ToLower());\n Console.WriteLine($\"{account.GetBalance():F1}\");\n\n success = account.Withdraw(1000);\n Console.WriteLine(success.ToString().ToLower());\n }\n}\n```\n\n```typescript\nclass BankAccount {\n private accountNumber: string;\n private ownerName: string;\n private balance: number;\n\n constructor(accountNumber: string, ownerName: string) {\n this.accountNumber = accountNumber;\n this.ownerName = ownerName;\n this.balance = 0;\n }\n\n deposit(amount: number): void {\n if (amount > 0) {\n this.balance += amount;\n }\n }\n\n withdraw(amount: number): boolean {\n if (amount > 0 && this.balance >= amount) {\n this.balance -= amount;\n return true;\n }\n return false;\n }\n\n getBalance(): number {\n return this.balance;\n }\n}\n\nconst account = new BankAccount(\"123456\", \"John Doe\");\naccount.deposit(1000);\nconsole.log(account.getBalance().toFixed(1));\n\nlet success = account.withdraw(500);\nconsole.log(success);\nconsole.log(account.getBalance().toFixed(1));\n\nsuccess = account.withdraw(1000);\nconsole.log(success);\n```\n\n\n---\n\n# Exercise 2: Library Book\n\n\n**Problem:** Create a `Book` class for a library management system.\n\n**Requirements:**\n\n- Fields: `title`, `author`, `isbn`, `isAvailable`\n- Constructor that initializes all fields (book starts as available)\n- `borrowBook()`: marks book as unavailable if currently available, returns success/failure\n- `returnBook()`: marks book as available\n- `displayInfo()`: prints book details including availability status\n\n```java\nclass Book {\n // Add private fields: title (String), author (String), isbn (String), isAvailable (boolean)\n\n public Book(String title, String author, String isbn) {\n // Initialize fields. Book starts as available.\n }\n\n public boolean borrowBook() {\n // Mark book as unavailable if currently available\n // Return true if successful, false if already borrowed\n return false;\n }\n\n public void returnBook() {\n // Mark book as available\n }\n\n public void displayInfo() {\n // Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n }\n}\n\n// Test your implementation\npublic class Main {\n public static void main(String[] args) {\n Book book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.displayInfo();\n\n boolean success = book.borrowBook();\n System.out.println(\"Borrow successful: \" + success);\n book.displayInfo();\n\n success = book.borrowBook();\n System.out.println(\"Borrow successful: \" + success);\n\n book.returnBook();\n book.displayInfo();\n }\n}\n```\n\n```python\nclass Book:\n def __init__(self, title: str, author: str, isbn: str):\n # Initialize fields: title, author, isbn, is_available (starts as True)\n pass\n\n def borrow_book(self) -> bool:\n # Mark book as unavailable if currently available\n # Return True if successful, False if already borrowed\n return False\n\n def return_book(self) -> None:\n # Mark book as available\n pass\n\n def display_info(self) -> None:\n # Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n pass\n\nif __name__ == \"__main__\":\n book = Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\")\n book.display_info()\n\n success = book.borrow_book()\n print(f\"Borrow successful: {str(success).lower()}\")\n book.display_info()\n\n success = book.borrow_book()\n print(f\"Borrow successful: {str(success).lower()}\")\n\n book.return_book()\n book.display_info()\n```\n\n```cpp\n#include \n#include \nusing namespace std;\n\nclass Book {\nprivate:\n // Add private fields: title (string), author (string), isbn (string), isAvailable (bool)\n\npublic:\n Book(const string& title, const string& author, const string& isbn) {\n // Initialize fields. Book starts as available.\n }\n\n bool borrowBook() {\n // Mark book as unavailable if currently available\n // Return true if successful, false if already borrowed\n return false;\n }\n\n void returnBook() {\n // Mark book as available\n }\n\n void displayInfo() const {\n // Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n }\n};\n\nint main() {\n Book book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.displayInfo();\n\n bool success = book.borrowBook();\n cout << \"Borrow successful: \" << boolalpha << success << endl;\n book.displayInfo();\n\n success = book.borrowBook();\n cout << \"Borrow successful: \" << success << endl;\n\n book.returnBook();\n book.displayInfo();\n\n return 0;\n}\n```\n\n```go\npackage main\n\nimport \"fmt\"\n\ntype Book struct {\n\t// Add private fields: title (string), author (string), isbn (string), isAvailable (bool)\n}\n\nfunc NewBook(title string, author string, isbn string) *Book {\n\t// Initialize fields. Book starts as available.\n\treturn &Book{}\n}\n\nfunc (b *Book) BorrowBook() bool {\n\t// Mark book as unavailable if currently available\n\t// Return true if successful, false if already borrowed\n\treturn false\n}\n\nfunc (b *Book) ReturnBook() {\n\t// Mark book as available\n}\n\nfunc (b *Book) DisplayInfo() {\n\t// Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n\tfmt.Println()\n}\n\nfunc main() {\n\tbook := NewBook(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\")\n\tbook.DisplayInfo()\n\n\tsuccess := book.BorrowBook()\n\tfmt.Printf(\"Borrow successful: %t\\n\", success)\n\tbook.DisplayInfo()\n\n\tsuccess = book.BorrowBook()\n\tfmt.Printf(\"Borrow successful: %t\\n\", success)\n\n\tbook.ReturnBook()\n\tbook.DisplayInfo()\n}\n```\n\n```csharp\nusing System;\n\npublic class Book\n{\n // Add private fields: _title (string), _author (string), _isbn (string), _isAvailable (bool)\n\n public Book(string title, string author, string isbn)\n {\n // Initialize fields. Book starts as available.\n }\n\n public bool BorrowBook()\n {\n // Mark book as unavailable if currently available\n // Return true if successful, false if already borrowed\n return false;\n }\n\n public void ReturnBook()\n {\n // Mark book as available\n }\n\n public void DisplayInfo()\n {\n // Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n }\n}\n\npublic class Program\n{\n public static void Main()\n {\n var book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.DisplayInfo();\n\n bool success = book.BorrowBook();\n Console.WriteLine($\"Borrow successful: {success.ToString().ToLower()}\");\n book.DisplayInfo();\n\n success = book.BorrowBook();\n Console.WriteLine($\"Borrow successful: {success.ToString().ToLower()}\");\n\n book.ReturnBook();\n book.DisplayInfo();\n }\n}\n```\n\n```typescript\nclass Book {\n // Add private fields: title (string), author (string), isbn (string), isAvailable (boolean)\n\n constructor(title: string, author: string, isbn: string) {\n // Initialize fields. Book starts as available.\n }\n\n borrowBook(): boolean {\n // Mark book as unavailable if currently available\n // Return true if successful, false if already borrowed\n return false;\n }\n\n returnBook(): void {\n // Mark book as available\n }\n\n displayInfo(): void {\n // Print: \"Title by Author (ISBN: isbn) - Available\" or \"- Borrowed\"\n }\n}\n\n// Test your implementation\nconst book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\nbook.displayInfo();\n\nlet success = book.borrowBook();\nconsole.log(`Borrow successful: ${success}`);\nbook.displayInfo();\n\nsuccess = book.borrowBook();\nconsole.log(`Borrow successful: ${success}`);\n\nbook.returnBook();\nbook.displayInfo();\n```\n\n#### Solutions\n\n```java\nclass Book {\n private String title;\n private String author;\n private String isbn;\n private boolean isAvailable;\n\n public Book(String title, String author, String isbn) {\n this.title = title;\n this.author = author;\n this.isbn = isbn;\n this.isAvailable = true;\n }\n\n public boolean borrowBook() {\n if (isAvailable) {\n isAvailable = false;\n return true;\n }\n return false;\n }\n\n public void returnBook() {\n isAvailable = true;\n }\n\n public void displayInfo() {\n String status = isAvailable ? \"Available\" : \"Borrowed\";\n System.out.println(title + \" by \" + author + \" (ISBN: \" + isbn + \") - \" + status);\n }\n}\n\npublic class Main {\n public static void main(String[] args) {\n Book book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.displayInfo();\n\n boolean success = book.borrowBook();\n System.out.println(\"Borrow successful: \" + success);\n book.displayInfo();\n\n success = book.borrowBook();\n System.out.println(\"Borrow successful: \" + success);\n\n book.returnBook();\n book.displayInfo();\n }\n}\n```\n\n```python\nclass Book:\n def __init__(self, title: str, author: str, isbn: str):\n self._title = title\n self._author = author\n self._isbn = isbn\n self._is_available = True\n\n def borrow_book(self) -> bool:\n if self._is_available:\n self._is_available = False\n return True\n return False\n\n def return_book(self) -> None:\n self._is_available = True\n\n def display_info(self) -> None:\n status = \"Available\" if self._is_available else \"Borrowed\"\n print(f\"{self._title} by {self._author} (ISBN: {self._isbn}) - {status}\")\n\nif __name__ == \"__main__\":\n book = Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\")\n book.display_info()\n\n success = book.borrow_book()\n print(f\"Borrow successful: {str(success).lower()}\")\n book.display_info()\n\n success = book.borrow_book()\n print(f\"Borrow successful: {str(success).lower()}\")\n\n book.return_book()\n book.display_info()\n```\n\n```cpp\n#include \n#include \nusing namespace std;\n\nclass Book {\nprivate:\n string title;\n string author;\n string isbn;\n bool isAvailable;\n\npublic:\n Book(const string& title, const string& author, const string& isbn)\n : title(title), author(author), isbn(isbn), isAvailable(true) {}\n\n bool borrowBook() {\n if (isAvailable) {\n isAvailable = false;\n return true;\n }\n return false;\n }\n\n void returnBook() {\n isAvailable = true;\n }\n\n void displayInfo() const {\n string status = isAvailable ? \"Available\" : \"Borrowed\";\n cout << title << \" by \" << author << \" (ISBN: \" << isbn << \") - \" << status << endl;\n }\n};\n\nint main() {\n Book book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.displayInfo();\n\n bool success = book.borrowBook();\n cout << \"Borrow successful: \" << boolalpha << success << endl;\n book.displayInfo();\n\n success = book.borrowBook();\n cout << \"Borrow successful: \" << success << endl;\n\n book.returnBook();\n book.displayInfo();\n\n return 0;\n}\n```\n\n```go\npackage main\n\nimport \"fmt\"\n\ntype Book struct {\n\ttitle string\n\tauthor string\n\tisbn string\n\tisAvailable bool\n}\n\nfunc NewBook(title, author, isbn string) *Book {\n\treturn &Book{\n\t\ttitle: title,\n\t\tauthor: author,\n\t\tisbn: isbn,\n\t\tisAvailable: true,\n\t}\n}\n\nfunc (b *Book) BorrowBook() bool {\n\tif b.isAvailable {\n\t\tb.isAvailable = false\n\t\treturn true\n\t}\n\treturn false\n}\n\nfunc (b *Book) ReturnBook() {\n\tb.isAvailable = true\n}\n\nfunc (b *Book) DisplayInfo() {\n\tstatus := \"Borrowed\"\n\tif b.isAvailable {\n\t\tstatus = \"Available\"\n\t}\n\tfmt.Printf(\"%s by %s (ISBN: %s) - %s\\n\", b.title, b.author, b.isbn, status)\n}\n\nfunc main() {\n\tbook := NewBook(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\")\n\tbook.DisplayInfo()\n\n\tsuccess := book.BorrowBook()\n\tfmt.Printf(\"Borrow successful: %t\\n\", success)\n\tbook.DisplayInfo()\n\n\tsuccess = book.BorrowBook()\n\tfmt.Printf(\"Borrow successful: %t\\n\", success)\n\n\tbook.ReturnBook()\n\tbook.DisplayInfo()\n}\n```\n\n```csharp\nusing System;\n\npublic class Book\n{\n private string _title;\n private string _author;\n private string _isbn;\n private bool _isAvailable;\n\n public Book(string title, string author, string isbn)\n {\n _title = title;\n _author = author;\n _isbn = isbn;\n _isAvailable = true;\n }\n\n public bool BorrowBook()\n {\n if (_isAvailable)\n {\n _isAvailable = false;\n return true;\n }\n return false;\n }\n\n public void ReturnBook()\n {\n _isAvailable = true;\n }\n\n public void DisplayInfo()\n {\n string status = _isAvailable ? \"Available\" : \"Borrowed\";\n Console.WriteLine($\"{_title} by {_author} (ISBN: {_isbn}) - {status}\");\n }\n}\n\npublic class Program\n{\n public static void Main()\n {\n var book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\n book.DisplayInfo();\n\n bool success = book.BorrowBook();\n Console.WriteLine($\"Borrow successful: {success.ToString().ToLower()}\");\n book.DisplayInfo();\n\n success = book.BorrowBook();\n Console.WriteLine($\"Borrow successful: {success.ToString().ToLower()}\");\n\n book.ReturnBook();\n book.DisplayInfo();\n }\n}\n```\n\n```typescript\nclass Book {\n private title: string;\n private author: string;\n private isbn: string;\n private isAvailable: boolean;\n\n constructor(title: string, author: string, isbn: string) {\n this.title = title;\n this.author = author;\n this.isbn = isbn;\n this.isAvailable = true;\n }\n\n borrowBook(): boolean {\n if (this.isAvailable) {\n this.isAvailable = false;\n return true;\n }\n return false;\n }\n\n returnBook(): void {\n this.isAvailable = true;\n }\n\n displayInfo(): void {\n const status = this.isAvailable ? \"Available\" : \"Borrowed\";\n console.log(`${this.title} by ${this.author} (ISBN: ${this.isbn}) - ${status}`);\n }\n}\n\nconst book = new Book(\"The Pragmatic Programmer\", \"David Thomas\", \"978-0135957059\");\nbook.displayInfo();\n\nlet success = book.borrowBook();\nconsole.log(`Borrow successful: ${success}`);\nbook.displayInfo();\n\nsuccess = book.borrowBook();\nconsole.log(`Borrow successful: ${success}`);\n\nbook.returnBook();\nbook.displayInfo();\n```\n","pageType":"lld-interviews"}

Exercise: Classes and Objects

Exercise 1: Bank Account

Exercise 2: Library Book

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