Object-oriented programming (OOP) is central to modern software development, offering modularity, reusability, and structured code that meets complex application demands. For ICT technicians in Kenya, mastering OOP principles in C++ empowers them to develop scalable and maintainable systems for diverse sectors such as banking, healthcare, and public administration. This chapter focuses on implementing objects and classes in C++ and declaring object methods, ensuring practical skills aligned with professional standards and workplace procedures.

3.1 Implementing Objects and Classes in C++ Object-Oriented Language

In professional ICT environments in Kenya, understanding how to implement objects and classes in C++ is fundamental to creating robust software solutions. These constructs encapsulate data and behaviours, enabling technicians to model real-world entities efficiently. Proper implementation aligns with industry practices, enhancing maintainability and collaboration in development teams.

3.1.1 Overview of Objects and Classes in Programming OOP Skills

Objects and classes form the foundation of object-oriented programming, allowing for abstraction and encapsulation of data and functions. A class acts as a blueprint defining attributes (data members) and behaviours (member functions or methods) common to all objects instantiated from it. An object is a specific instance of a class with its own unique state.

• Encapsulation: Classes bundle data and related methods, restricting direct access to internal states, which safeguards data integrity. For example, a banking application at Equity Bank uses classes to represent accounts, preventing unauthorized modifications to balances.
• Abstraction: Classes expose only necessary details through methods, hiding complex implementation. In a hospital management system, patient details are encapsulated, enabling staff to access only relevant information.
• Inheritance: Classes can inherit properties and methods from parent classes, promoting code reuse. A SACCO management system might model different member types sharing common attributes.
• Polymorphism: Methods can have multiple forms, allowing flexibility in behaviour. For example, a retail inventory system uses polymorphism to process different product categories with a common interface.
• Modularity: Classes enable breaking down programs into manageable units, facilitating team development and debugging in county government software projects.

3.1.2 Ensuring Implementation Aligns with Work Procedures

Aligning class and object implementation with organizational work procedures ensures software supports operational workflows and compliance requirements. Kenyan institutions such as KRA require systems that reflect structured processes for data handling and reporting.

Development Standards Compliance

• Adhering to coding standards reduces errors and improves readability. For instance, TSC mandates clear documentation and consistent naming conventions in educational software.
• Version control practices like using Git ensure collaborative development aligns with project timelines.
• Commenting and documenting classes and methods support future maintenance and audits.

Workflow Integration

• Classes should model real-world entities accurately to reflect business processes. A county health records system should represent patients, appointments, and medical staff as distinct classes.
• Implementation must support data validation rules defined in organizational policies, such as mandatory fields in loan application systems at SACCOs.
• Error handling within methods must follow institutional protocols to prevent system crashes and data loss.

Testing and Quality Assurance

• Unit tests for classes verify correct behaviour before deployment. Banks like KCB conduct rigorous testing to safeguard transaction integrity.
• Code reviews by peers ensure adherence to work procedures and identify logical errors early.
• Continuous integration tools automate testing and deployment, maintaining software reliability.

3.1.3 Structure of Classes and Objects in C++

C++ classes consist of data members and member functions, with access specifiers controlling visibility. Objects are instances created from these classes, each with independent data.

• Class Declaration: Defined using the class keyword, followed by the class name and body enclosed in braces. For example, class Customer { ... };.
• Access Specifiers: private, protected, and public control access to members. Private members cannot be accessed outside the class, protecting internal data.
• Constructors and Destructors: Special methods initialize objects and clean up resources. Constructors like Customer() set default values; destructors release memory.
• Member Functions: Define behaviours, can modify object state or provide information.
• Object Instantiation: Objects are created by declaring variables of the class type, e.g., Customer c1;.

3.1.4 Practical Example of Class and Object Implementation

Consider a retail application for a supermarket chain in Nairobi. The class Product models items with attributes like productID, name, price, and methods to update stock or calculate discounts.

class Product {
private:
    int productID;
    string name;
    double price;
public:
    Product(int id, string n, double p) {
        productID = id;
        name = n;
        price = p;
    }
    void updatePrice(double newPrice) {
        price = newPrice;
    }
    double getPrice() {
        return price;
    }
};

An object Product p1(101, "Maize Flour", 120.0); represents a specific product. This encapsulation supports clear, maintainable code that aligns with business logic in retail inventory management.

Chapter Summary

This chapter explored the fundamental skills required to demonstrate object-oriented programming using the C++ language. It began with an introduction to implementing objects and classes, emphasizing the need to align coding practices with established work procedures. The discussion then moved to declaring object methods, highlighting the importance of defining methods that meet application requirements and adopting best practices for naming and functionality. The role and implementation of namespaces were examined to organize code and prevent naming conflicts. Concepts of data abstraction were defined, outlining their significance and how they are applied within object-oriented programming. The chapter also covered object encapsulation, explaining its definition, importance, and practical implementation. Further, it addressed class templates and detailed class inheritance, including the distinction between base and derived classes, inheritance relationships, and various types of inheritance. Finally, the chapter concluded with an analysis of class polymorphism, defining the concept, its importance, and how it is implemented to allow objects to take multiple forms in C++ programming.