Program Testing

• Lets the programmer know if the program is working
• Various errors:
• Syntax errors – when instructions do not follow the specified format
• Runtime errors – appear while the program is running; instructions that the computer cannot execute
• Logic error – logical design error; incorrect formulas or calculations

Program Documentation

• Programmers insert comments into the code
• Function descriptions are also included and these are also considered as comments

Procedural Programming and Object-Oriented Programming

What is procedural programming?

• It is a concept/paradigm
• Seen as a way of solving problems using a sequence of steps
• A programming language that supports the procedural paradigm is called a procedural language (machine language, assembly language, C and other 3^rd generation languages)

What is an Algorithm?

• An algorithm is a set of steps for carrying out a task that can be written down and implemented
• Expressed as instructions
• To design an algorithm; take note of the steps to be taken in manually solving the problem

Ways of expressing an algorithm

• Structured English – subset of English; has limited selection of sentences that reflect processing activities
• Pseudo code – notational system for algorithms that is a mixture of English and a programming language
• Flowchart – graphical representation of the order of execution of instructions

Advantages and Disadvantages

Advantages

• Programs run quickly
• System resources are used efficiently
• Classic approach

Disadvantages

• Does not fit with complex algorithms
• Forces programmers to think of problems as a series of steps

Object-Oriented programming

• Based on the idea that the solution for a problem can be visualized in terms of objects that interact
• Object – a unit of data that represents an abstract or real-world entity; from a class
• Class – a template for a group of objects with similar characteristics

More on Classes

·        UML (Unified Modeling Language)

·        Class attribute – defines the characteristics of a set of objects

o       Public attribute – available for use anywhere in the program

o       Private attribute – can only be accessed where it is defined

·        Inheritance – passing certain characteristics from one class to other classes

·        Super class – any class from which attributes can be inherited

·        Subclass – any class that inherits from a super class

What is a Method?

• A method is a segment of code that defines an action
• It can perform a variety of tasks such as collecting input, performing calculations, comparing data, and producing output
• Polymorphism – overloading; redefine a method in a subclass

Advantages and disadvantages

Advantages

• Similar to the way human beings see the world
• Allows encapsulation (hiding object details and methods) that lets objects be reused, modified and repurposed

Disadvantages

• Requires more memory and processing resources