Understanding Computers
Today and Tomorrow 12th Edition
Chapter 13:
Program Development
and Programming
Languages
Learning Objectives
• Understand the differences between structured
programming, object-oriented programming (OOP),
aspect-oriented programming (AOP), and adaptive
software development.
• Identify and describe the activities involved in the
program development life cycle (PDLC).
• Understand what constitutes good program design
and list several tools that can be used by computer
professionals when designing a program.
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Learning Objectives
• Explain the three basic control structures and how
they can be used to control program flow during
execution.
• Discuss some of the activities involved with coding,
debugging, maintaining, documenting, and ensuring
the quality of programs.
• List some tools that can be used to speed up or
otherwise facilitate the program development process.
• Describe several programming languages in use
today.
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Overview
• This chapter covers:
– The most common approaches to program design
and development
– The steps in the program development life cycle
(PDLC)
– Tools that can facilitate program development
– Popular programming languages
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Approaches to Program Design
and Development
• Procedural programming: Focuses on the step-bystep instructions that tell the computer what to do
– Uses procedures (modules, subprograms): Smaller
sections of code that perform particular tasks
– Allows each procedure to be performed as many
times as needed without requiring multiple copies
of code
– Prior to procedural programming, programs were
one large set of instructions containing statements
that sent control to different parts of the program as
needed (i.e. GOTO statements)
– Structured programming: Breaks the program into
small chunks
• Top-down design
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Approaches to Program Design
and Development
– Variables: Named memory locations
that are defined for a program
• Used to store the current value of
data items used in the program
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Approaches to Program Design
and Development
• Object-oriented programming (OOP): Programs
consist of a collection of objects
– Objects: Contain data and methods to be used with
that data
– Class: Group of objects that share some common
properties
– Instance: An individual object in a class
– Attributes: Data about the state of an object
– Methods:
Perform
actions on an
object
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Approaches to Program Design
and Development
• Aspect-oriented programming (AOP): Breaks program
into small pieces that overlap in functionality as little
as possible
– Program components can be developed and
modified individually, and easily reused
• Adaptive software development: Designed to make
program development faster and more efficient and
focus on adapting the program as it is being written
– Iterative: Cyclical approach that allows the
repetition of steps and tasks as needed
– Incremental: Developing one piece at a time
– Includes RAD (rapid application development) and
extreme programming (XP)
– More recent adaptive software development
approaches are called agile software development
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The Program Development Life
Cycle (PDLC)
• Program development: The process of creating
application programs
• Program development life cycle (PDLC):The steps
involved with creating programs:
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The Program Development Life
Cycle (PDLC)
• Problem analysis: The problem is considered and the
program specifications are developed
– Specifications developed during the SDLC are
reviewed by the systems analyst and the
programmer (the person who will code the
program)
– Goal: To understand the functions the software
must perform
– Documentation: Includes program specifications
(what it does, timetable, programming language to
be used, etc)
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The Program Development Life
Cycle (PDLC)
• Program design: The set of steps needed in order for
the program to perform the tasks it is supposed to
perform (algorithm) is developed
– Good program design is extremely important
– Program design tools
• Structure charts: Depict the overall organization
of a program
• Flowcharts: Show
graphically step-by-step
how a computer program
will process data
• Use special symbols and
relational operators
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Flowcharts
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The Program Development Life
Cycle (PDLC)
• Pseudocode: Uses English-like statements to
outline the logic of a program
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The Program Development Life
Cycle (PDLC)
• Unified Modeling Language (UML) Models: Set
of standard notations for creating business
models
– Widely used in object-oriented programs
– Includes class diagrams, use case diagrams,
etc.
• Business Processing Modeling Notation
(BPMN): Graphical notation used to depict the
steps in a business process
– Expresses business processes graphically
using Business Process Diagrams
– Look similar to flowcharts
– Designed to be understood by everyone
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Unified Modeling Language (UML)
Models
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The Program Development Life
Cycle (PDLC)
– Control structure: A Pattern for controlling the flow
of logic in a computer program
• Sequence control structure: Series of
statements that follow one another
• Selection control structure: Multiple paths,
direction depends on result of test
– If-then-else
– Case
• Repetition control structure: Repeat series of
steps
– Do-while
– Do-until
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Control Structures
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Control Structures
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The Program Development Life
Cycle (PDLC)
– Good program design:
• Saves time
• Creates better programs
– Good program design principles:
• Be specific
– All things the program must do need to be
specified
• One-entry-point/one-exit-point rule
• No infinite loops or other logic errors
– Infinite loop: Series of steps that repeat
forever
– Design should be tested to ensure logic is correct
• Desk check; tracing tables
– Documentation: Includes design specifications
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Good Program Design
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Program Design Testing
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The Program Development Life
Cycle (PDLC)
• Program coding: The process of writing the
programming language statements to create a
computer program
– When choosing a programming language,
consider:
• Suitability to the application
• Integration with other programs
• Standards for the company
• Programmer availability
• Portability if being run on multiple platforms
• Development speed
– Coding creates source code
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Coding Standards
– Coding standards: A list of rules designed to
standardize programming styles
• Make programs more universally readable and
easier to maintain
• Includes the proper use of comments to:
– Identify the programmer and last
modification date
– Explain variables used in the program
– Identify the main parts of the program
– Reusable code: Generic code segments that can
be used over and over again with minor
modifications
• Can greatly reduce development time
– Documentation: Includes documented source code
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Coding Standards
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The Program Development Life
Cycle (PDLC)
• Program debugging and testing: The process of
ensuring a program is free of errors (bugs) and works
as it is supposed to
– Before they can be debugged, coded programs
need to be translated into executable code
• Source code: Coded program before it is
compiled
• Object code: Machine language version of a
program
• Language translator: Program that converts
source code to machine language
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The Program Development Life
Cycle (PDLC)
• Types of language translators:
– Compilers: Combines
program with other
object modules and
creates a finished
executable program
– Interpreters:
Translates one line of
code at one time
– Assemblers: Convert
assembly language
programs
into
machine
language
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The Program Development Life
Cycle (PDLC)
̶
Chapter 13
Preliminary debugging: Finds initial errors
• Compiler errors: Must be corrected before the
logic of the program can be tested
• Syntax errors: Occur when the programmer
has not followed the rules of the programming
language
̶ Program won’t run; usually an error
message is displayed
• Run time error: Occurs when the program is
running
̶ Often logic errors: Program will run but
produces incorrect results
̶ Dummy print statements can help locate
logic errors and other run time errors
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Preliminary Debugging
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Preliminary Debugging
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The Program Development Life
Cycle (PDLC)
– Testing occurs after the program appears to be
correct to find any additional errors
• Should use good test data
• Tests conditions that will occur when the
program is implemented
• Should check for coding omissions (product
quantity allowed to be < 0, etc.)
• Alpha test (inside organization)
• Beta test (outside testers)
– Documentation: Completed program package
(user’s manual, description of software commands,
troubleshooting guide to help with difficulties, etc.)
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The Program Development Life
Cycle (PDLC)
• Program implementation and maintenance: Installing
and maintaining the program
– Once the system containing the program is up and
running, the implementation process is complete
– Program maintenance: Process of updating
software so it continues to be useful
• Very costly
– Documentation: Amended program package
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Tools for Facilitating
Program Development
• Application Lifecycle Management (ALM): Creating
and managing an application during its entire lifecycle,
from design through testing
– Tools include:
• Requirements management: Keeping track of
and managing the information needs of users
– Requirements definition software
– Requirements management software
• Configuration management: Keeping track of
the progress of a program development project
• Program design tools to generate diagrams,
code, etc.
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Tools for Facilitating
Program Development
• Application generator: Software product that enables
users to code new applications quickly
– Macro recorders: Record and play back a series of
keystrokes
– Report and form generators: GUI tools that enable
individuals to
prepare reports
and forms
quickly
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Tools for Facilitating
Program Development
• Device software development tools: Assist with
developing software to be used on devices, such as
cars, ATM machines, consumer devices, etc
• Software development kits (SDK): Programming
package designed for a particular platform that
enables programmers to develop applications more
quickly and easily
– Released by hardware or software companies
(Microsoft, Apple, etc.)
• Application Program Interfaces (API): An interface
designed to help applications interface with a
particular operating system
– Often used in conjunction with Web sites
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Programming Languages
• Programming language: A set of rules used to write
computer programs
– To write a program, you need appropriate software
for the programming language you will be using
• Categories of programming languages
– Low-level languages: Difficult to code in; machine
dependent
• Machine language: 1s and 0s
• Assembly language: Includes some words and
symbols
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Programming Languages
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Programming Languages
– High-level languages: Closer to natural languages
and so are easier to write in
• Machine independent
• Includes third-level procedural languages such
as FORTRAN, BASIC, COBOL, Pascal, and C,
as well as newer object-oriented languages
such as Visual Basic, C++, C#, Python, Ruby,
and Java
– Fourth-generation languages (4GLs): Even closer
to natural languages and easier to work with than
3GLs
• Declarative rather than procedural
• Includes structured query language (SQL) used
with databases
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Programming Languages
– Natural programming languages: Users can
communicate in their native language
• Doesn’t have to follow program syntax
• In the infancy stage
– Visual programming languages: Uses a visual
programming environment
• User can use mouse and graphical interface
and the code is automatically generated
• Visual versions of many programming
languages
• Visual programming environment (VPE): Use
visual elements to assist in program
development but still require some coding
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Common Programming Languages
• FORTRAN: High-level programming language used
for mathematical, scientific, and engineering
applications
– Efficient for math
and scientific
applications
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Common Programming Languages
• COBOL: Designed for business transaction
processing
– Makes extensive use of modules and submodules
– Being phased out in many organizations
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Common Programming Languages
• Pascal: Created as a teaching tool to encourage
structured programming
– Contains a variety of control structures used to
manipulate modules systematically
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Common Programming Languages
• BASIC: Easy-to-learn, high-level programming
language that was developed to be used by beginning
programmers
– Visual Basic: Object-oriented version of BASIC
which helps programmers quickly and easily create
programs through the use of a visual environment
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Common Programming Languages
• C: Designed for system programming
• C++, and C#: Object-oriented versions of C
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Common Programming Languages
• Java: High-level, object-oriented programming
language frequently used for Web-based applications
– Platform independence is one of Java’s biggest
advantages
– Any operating system or browser that understands
Java (compiled Java programs) can run Java
bytecode applications
– Is one of the most popular programming languages
today
– Can be used to write Java applets
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Common Programming Languages
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Common Programming Languages
• Python: Open-source, dynamic, object-oriented
language that can be used to develop a variety of
applications
– Gaming, scientific, database, and Web applications
– Only recently gaining a following
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Common Programming Languages
• Ruby: Open-source, object-oriented language that can
be used to create general-purpose or Web
applications
– Uses a syntax that is fairly easy to read and write,
allowing programmers to create database-driven
Web
applications
easily and
quickly
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Summary
• Approaches to Program Design and Development
• The Program Development Life Cycle (PDLC)
• Tools for Facilitating Program Development
• Programming Languages
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