1 chapter 13 understanding computers, 11 th edition 13 program development and programming languages...

1Chapter 13 Understanding Computers, 11th Edition

13Program Development

and Programming Languages

TODAY AND TOMORROW

11th Edition

CHAPTERCHAPTER


Learning Objectives Understand the differences between structured

programming, object-oriented programming (OOP), and aspect-oriented programming (AOP).

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.


Learning Objectives, Cont’d 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.


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 Programming language categories Popular programming languages


Approaches to Program Design andDevelopment

Structured programming: programs are separated into modules or subprograms, and instructions are executed one after the other, calling the subprograms when needed


Approaches to Program Design andDevelopment, Cont’d

Object-oriented programming (OOP): programs consist of a collection of objects Objects: contain data and methods to

be used with that data Variables: data about the state of an

object Methods: perform actions on the

object


Approaches to Program Design andDevelopment, Cont’d

Object-oriented programming (OOP), cont’d: Polymorphism: Multiple methods with the same

name can perform different actions with different types of objects

Inheritance: all objects inherit the characteristics of the class in which it belongs

Aspect-oriented programming (AOP): functions are clearly separated so program components can be developed and modified individually, and the components can be easily reused


The Program Development Life Cycle (PDLC)

Program development: the process of creating programs

Program development life cycle (PDLC): the steps involved with creating programs


Problem Analysis Problem analysis: the step in the program

development life cycle in which the problem is considered and the program specifications are developed Specifications developed during the SDLC are

reviewed by the systems analyst and the programmer

Goal: to understand the functions the software must perform

Documentation: Program specifications (what it does, timetable, programming language to be used, etc)


Program Design Program design: the step in the program

development life cycle in which the program specifications are expanded into a complete design of the new program

Program design tools Structure charts (depict the overall organization of a

program) Program flowcharts (show graphically step-by-step

how a computer program will process data


Program Design, Cont’d Program design tools,

cont’d Pseudocode: uses

English-like statements to outline the logic of a program


Program Design, Cont’d Program design tools, cont’d

Data modeling: illustrates the data in an application

Often used when designing an object-oriented program

Each object is identified along with its corresponding class, class properties, and variables


Control structure: a pattern for controlling the flow of logic in a computer program Sequence control structure (series of procedures

that follow one another) Selection control structure

If-then-else Case

Repetition control structure Do-while Do-until

Program Design, Cont’d


Program Design, Cont’d Good program design = essential

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 (should trace

flowchart to check logic) Documentation: Design specifications (expressed using

flowcharts, pseudocode, structure charts, data models)


Program Coding Coding: the process of writing the programming

language statements to create a computer program Need to choose a programming language; consider:

Suitability Integration Standards Programmer availability Portability Development speed


Program Coding, Cont’d 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


Program Coding, Cont’d Reusable code: generic code segments that can be

used over and over again with minor modifications Can greatly reduce development time

Data Dictionary: contains information about the data used in a program, such as the names, descriptions, and rules of usage for every variable and data item used in the program Can help consistency during coding

Documentation: Documented source code (including comments)


Program Debugging and Testing Debugging: the process of ensuring a program is free

of errors (bugs) 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


Program Debugging and Testing, Cont’d

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)



Preliminary debugging 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 Logic errors: occur when the logic in a program is

wrong Program will run but produces incorrect results Dummy print statements can help locate logic

errors



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.)


Program Implementation and Maintenance

Program implementation: implemented as part of the SDLC 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


Tools for Facilitating Program Development

Application Lifecycle Management (ALM): describes complete systems that can be used to create and manage an application throughout its entire lifecycle,from design through testing



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 enables individuals to prepare reports and forms quickly

Often built into database programs



Software-asset management tools: designed to help facilitate reusable code Store and organized tested software components

so they can be inserted into new applications quickly and efficiently

Device software development tools: assist with developing software to be used on devices, such as cars, ATM machines, consumer devices, etc.


Programming Languages Programming language: a set of rules used to write

computer programs Programs are written using a programming

software package for the selected programming language

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)


Programming Languages Categories of programming languages, cont’d

High-level languages (closer to natural languages; easier to write in)

Includes third-level procedural languages such as BASIC, COBOL, Pascal, and C, as well as newer object-oriented languages such as C++, C#, and Java)

Fourth-generation languages (4GLs): even closer to natural languages and easier to work with than 3GLs

Includes structured query language (SQL) used with databases


Programming Languages Categories of programming languages, cont’d

Natural programming languages (user can communicate in their native language)

Doesn’t have to follow program syntax In the infancy stage

Visual programming languages (uses a graphical programming environment)

User can use mouse and graphical interface and the code is automatically generated

Visual versions of many programming languages


Popular Programming Languages FORTRAN: high-level programming language used

for mathematical, scientific, and engineering applications Efficient


COBOL: designed for business transaction processing Being

phased out in many organ-izations

Popular Programming Languages, Cont’d


Pascal: used to teach structured programming; especially appropriate for use in math and science appli-cations



BASIC: easy-to-learn, high-level programming language that was developed to be used by beginning programmers

Visual Basic:object-oriented, fourth-generation version of BASIC



C, C++, and C#: versions of the highly efficient C programming language C++ and

C# are object-oriented



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 bytecode (compiled Java programs) can run Java applications

Is one of the most popular programming languages today



Java, cont’d Java applets: small programs that are designed to

be inserted into Web pages and run using a Java-enabled Web browser

The .class file containing the applet’s code must be stored with the Web site files

HTML code is used to insert the applet and specify parameters to customize the applet

Java applets that run on the server instead of on the client computer are called servlets



Summary Approaches to Program Design and Development

The Program Development Life Cycle (PDLC)


Programming Languages

1 chapter 13 understanding computers, 11 th edition 13 program development and programming languages...

Documents

program specifications

program components

program development

program designprogram

good program design

programming languagestoday

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