Computers Are Your Future Twelfth Edition Chapter 11: Programming Languages and Program Development Copyright © 2012 Pearson Education, Inc. Publishing

Computers Are Your FutureTwelfth Edition

Chapter 11: Programming Languages and Program Development

Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 1

Programming Languages

and Program Development


Objectives• Explain what a programming

language is and how it works.• Explain the development of

programming languages over the years and the benefits and drawbacks of high-level programming languages.

• Explain how object-oriented languages attempt to remedy the shortcomings of earlier languages.


Objectives• List several popular object-oriented

languages and explain their advantage over older languages.

• List the six phases of the program development life cycle (PDLC) and explain why the PDLC is needed.


Objectives• Explain why defining the problem in

a top-down design manner leads to programs that are easier to debug and maintain.

• Differentiate between problems that can arise in the testing and debugging phase as syntax and logic errors.



and How They Work• Programming

o Process used to create software programs

• Programmerso People who use programming languages to

create software applications

• Programming languageso Consist of a vocabulary and a set of rules

called syntax



and How They Work• Interface

o Point of interaction between components, such as the interaction between a user’s screen and the computer code, which results when running a program


Development of Programming Languages




• Compilers and interpreterso Source code—programming instructions in the

original form needed to translate a form that the computer can understand

o Code—programming instructions created by the programmers

o High-level language—language that mimics English; does not require a programmer to understand the intimate details of how hardware, especially the processor, handles data





• Compilers and interpreterso Compiler—utility program translates source

code into object codeo Executable program—code transformed

from object code ready to run programs that do not need to be altered

o Interpreter—translation program that does not produce object code—translates one line of source code at a time; executes the translated instruction


• Five generations of programming languageso Machineo Assemblyo Proceduralo Nonproceduralo Natural



• First-generation languageso Machine language

• Based on binary numbers• Only programming language that a

computer understands directly• Machine dependent



• Second-generation languageo Assembly language

• Low-level language• Programs use:

o Mnemonics—brief abbreviations for program instructions make assembly language easier to use

o Base-10 (decimal) numbers

• Must be translated into machine language by an assembler

• Occasionally used to create device driverso Programs to control devices attached to a computer and

game console programs



• Third-generation languageso High-level languages—do not require

programmers to know details relating to the processing of data

o Easier to read, write, and maintain than assembly and machine languages

o Source code must be translated by a language translator



• Third-generation languages (con’t.)o Spaghetti code—difficult to follow, messy in

design, prone to errors due to numerous GOTO statements

o Structured programming—set of quality standards; programs more verbose but more readable, reliable, and maintainableo GOTO statements forbiddeno Examples:

• Ada• Algol• Pascal



• Third-generation languages (con’t.)o Modular programming—dividing larger programs

into separate modules, each takes care of a specific function

o Information hiding—also known as encapsulation, modular programming makes it possible to hide details in sensitive applications

o Programming languages include:• Fortran• C


Development of Programming Languages• Procedural

languageso Provide detailed

instructions that are designed to carry out a specific action such as printing a formatted report

• Nonprocedural languageso Do not require

programmers to use step-by-step instructions



• Fourth-generation languageso Nonprocedural languageso Do not require step-by-step procedureso Examples

• Report generators (database reports)• Query languages

oSQL (Structured query language)—enables users to phrase simple or complex requests for data



• Fifth-generation languages o Natural languageo Still being perfectedo Nonproceduralo Use everyday language to program



• Object-oriented programming (OOP) o Programming technique based on data being

conceptualized as objects• Object—unit of computer information that

defines a data element that is used to model real-world objects

• Attributes define the data• Procedures or operations are called methods



• Object-oriented programming (OOP) (con’t.)o Class—blueprint or prototype from which objects

are madeo Inheritance—ability to pass on characteristics

from a class to subclasses



• Program development methodso Rapid application development (RAD)

• Reuses prebuilt objects• Possible because of OOP

o Joint application development (JAD)• Uses a team approach• Involves end users throughout development

o Agile software development techniques—use collaboration between teams to develop solutions to meet customer needs and company goalsCopyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 23


• Middlewareo Makes connections between applications on

multiple networkso Integral to modern information technology

based on XML, Web services, and service-oriented architecture


A Guide to Programming Languages:

One Size Doesn’t Fit All• Early high-level languages

o COBOL (Common Business-Oriented Language) • Used for business applications• Current focus is on editing aged code on mainframe

computerso Fortran (formula translator)

• Used for scientific/math/engineering applications• Being replaced by object-oriented and formula-

solving programs o Mathematica

• Used to handle all aspects of technical computing in a coherent and unified way

• Can manipulate a wide range of objects, using only a small number of basic elements



One Size Doesn’t Fit All• Structured and modular

languageso Required for large-scale program developmento Languages in widespread use:

• Ada• BASIC• Visual Basic

o Event-driven programming language that executes only in response to user actions

• C



One Size Doesn’t Fit All• Object-oriented languages

o Visual Studio.NET—Microsoft’s answer to Java and JavaScript

• Visual Basic.Net• Visual C++• Visual C#• F#—language that combines object-oriented

features with the assets of a functional languageo Functional language reflects the way people think

mathematically—useful in programs that express findings in mathematical form

• Integrated development environment (IDE)



One Size Doesn’t Fit All

• Web-based languageso Not considered programming languageso Tell the browser how to display text and

objectso Language types

• Markup• Scripting


A Guide to Programming Languages: One Size Doesn’t Fit

All

• Markup languages o Composed of a set of codes, or elements,

that uses tags to define how text and objects display

• Tags—markers that usually come in pairso Content—text that displays, lies between

the opening and closing tags



All

• Markup languages o HTML (Hypertext Markup Language)

• Used by Web programmers • Supports links to other documents, graphics, and audio and

video files.o XML (Extensible Markup Language)

• Enables programmers to capture specific types of data by creating their own elements

• Not a replacement for HTMLo XHTML (Extensible Hypertext Markup Language

• Newer version of HTML that uses XML to produce Web pages that are easily accessible by newer portable devices.



All• Markup languages (con’t.)

o WML (Wireless Markup Language)enables developers to create pages for wireless devices

o CSS (Cascading Style Sheets)defines the look and formatting of a Web page

• World Wide Web Consortium (W3C)o International group—develops Web standardso Develops protocols and guidelines that ensure

long-term growth for the Web



One Size Doesn’t Fit All• Scripting languages

o Create scripts—programs that control Web page actions or responses

• VBScript• ActiveX controls• JavaScript• ECMAScript• AJAX• JSON

o Used for serialization and transmitting structured data over a network

• PHPCopyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 32

The Program Development Life Cycle

• Program development life cycle (PDLC)o Organized plan for managing the

development of softwareo Consists of six phases, from problem

definition through program implementation and maintenance





• Phase 1: Defining the problemo Define the problem the program will solveo Define the program specifications, including

decisions regarding data input, required processing, output, and the user interface



• Phase 2: Designing the programo Program design—identifies components of the

program• Top-down program design—breaks

program into small, manageable, highly focused routineso Procedures, functions, or subroutines

• Structured design uses control structures—logical elements assembled in blocks of code that determine how subroutines will be programmed


The Program Development Life Cycle• Phase 2: Designing the program

(con’t.)o Basic control structures categories

• Sequence control structure—code performed in line-by-line order

• Selection control structure—also called a conditional or branch structure, this is a portion of code that leads to a block of code based on conditions being met

• Case control structure—portion of code that branches to extensive conditional coding

• Repetition control structure—also known as looping or iteration, this is a portion of code that repeats


The Program Development Life Cycle• Phase 2: Designing the

program (con’t.)o Algorithm

• Combination of control structures • Step-by-step description of how to arrive at a

solutiono Nesting

• Process of embedding control structures within one another




The Program Development Life Cycle• Phase 2: Designing the program

(con’t.)o Program design tools

• Structured charts—also called hierarchy charts, show top-down design of programs

• Flowcharts—use diagrams to show the logic of a program

• Unified Modeling Language (UML)—variation of flowcharting used to illustrate and document object-oriented systems during development

• Pseudocode—uses a stylized form of writing to describe logic





• Phase 3: Coding the programo Programmers convert algorithms into

programming codeo Syntax errors

• Mistakes in the construction of the programming commands

• Must be corrected for the program to run appropriately


The Program Development Life Cycle• Phase 4: Testing and

debugging the programo All errors, not just syntax errors, must be

removedo Logic errors

• Relate to problems in the solution’s design• Cause incorrect output• Program still runs despite logic errors

o Syntax errors and logic errors—bugso Debugging—process of eliminating errors


The Program Development Life Cycle• Phase 5: Documenting the

programo Documentation includes:

• Overview of program functionality• Tutorials• Thorough explanation of main features • Reference documentation of program commands• Description of error messages• Program design work, including structure charts,

pseudocode, and flowcharts


The Program Development Life Cycle• Phase 6: Implementing and maintaining the programo Test the program

• Have users work with the software• Correct errors

o Program maintenance• Fix program errors discovered by users• Conduct periodic evaluations on a regular basis• Make modifications as needed to update the

program or add featuresCopyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 45

Summary• Explain what a programming

language is and how it works.• Explain the development of

programming languages over the years and the benefits and drawbacks of high-level programming languages.

• Explain how object-oriented languages attempt to remedy the shortcomings of earlier languages.


Summary• List several popular object-oriented

languages and explain their advantage over older languages.

• List the six phases of the program development life cycle (PDLC) and explain why the PDLC is needed.


Summary• Explain why defining the problem in

a top-down design manner leads to programs that are easier to debug and maintain.

• Differentiate between problems that can arise in the testing and debugging phase as syntax and logic errors.


49

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Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall

Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall

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Computers Are Your Future Twelfth Edition Chapter 11: Programming Languages and Program Development Copyright © 2012 Pearson Education, Inc. Publishing