University of Maryland, Baltimore County 9

Linked Lists in Projects

• Key structure for programming projects involving data manipulation.

• Involves operations like insertion, deletion, and traversal.

Enums (Enumerations)

• Definition: A data type for group constants representing integers with descriptive names.

• Example: Seasons as an enum:

  • Values: Winter, Spring, Summer, Fall.

  • Compiler assigns: Winter = 0, Spring = 1, Summer = 2, Fall = 3.

• Usage:

  • Named types enable more readable code over unnamed integers.

  • Cannot assign invalid values to ENUM.

  • Example of unnamed types as constants allows easier readability but lacks type safety.

Operator Overloading

• A technique allowing operators to work with user-defined types (like classes).

• Key Ideas:

  • Enables syntactic sugar - p = q to assign contents in string types.

  • Commonly overloaded operators: +, -, ==, ++, --, and [] for arrays.

  • Example Implementation: Overloading the minus operator in a Money class.

    • Prevents incorrect member-wise subtraction (e.g., 6.01 - 0.20 leading to 6.00).

    • Syntax example:

      Money operator-(const Money& other);

Code Reuse in OOP

• Essential for efficient coding; reduces redundancy and potential errors.

• Inheritance: A mechanism of code reuse by creating a new class from an existing one.

• Examples of Object Relationships:

  • Inheritance (is-a relationship): e.g., A Dog is an Animal.

  • Composition (has-a relationship): A Car has an Engine.

  • Aggregation (has-a relationship): A Car has a Driver (independently existing).

Understanding Inheritance in Object-Oriented Design

• Base Class (Parent): Contains common characteristics; example - Vehicle class.

• Derived Class (Child): Inherits properties and methods from the parent; example - Car class inheriting from Vehicle.

• Syntax: class DeriveClass : public BaseClass {}.

  • Inherited attributes and functions become accessible in the child class.

Attributes of Classes and Objects

• Creating Object Relationships:

  • Classes can have attributes and methods that define characteristics and behaviors.

  • Example of the Person class:

    • Attributes: First name (m_fname), Last name (m_lname).

    • Derived classes like Student and Professor inherit these attributes.

Understanding Aggregations and Compositions

• Aggregation is a relationship where one class can exist independently of another.

• Composition implies a stronger lifecycle equality; if the parent is destroyed, so are the child components.

• Aggregation Example: Car aggregates Driver relationships with pointers rather than owning the objects.

Destructor and Memory Management

• Importance of managing memory when using new to prevent memory leaks.

• Proper destructors should be defined to free memory allocated with new when objects go out of scope.

• Example: Pointer vectors in a class that need explicit deletion on destruction to ensure no memory leaks occur.