Computers Are Your Future Tenth Edition Chapter 11: Programming Languages & Program Development Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall1

2 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America. Copyright © 2009 Pearson Education, Inc. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall

What You Will Learn Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall3 Explain what a programming language is. Contrast machine language and assembly language. Discuss the benefits and drawbacks of high-level programming languages. Explain how object-oriented languages attempt to remedy the shortcomings of earlier languages.

What You Will Learn 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. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall4

What You Will Learn Explain why top-down program design makes programs easier to debug and maintain. List the three basic types of control structures and the advantages of each. Differentiate between syntax errors and logic errors in programs. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall5

Programming Language & Program Development Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall6

Development of Program Languages Programming is the creation of software applications. Programmers are the people who create the software applications. A programming language is a language used by programmers to create programs or software that the computer understands. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall7

Development of Program Languages Syntax is the vocabulary and “grammar” of a programming language. Code is the programming instructions created by the programmers. Source code, the only form of code that humans can read, is program code in its original form. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall8

Development of Program Languages Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall9

Development of Program Languages There are five distinct programming language generations, or levels: Machine language Assembly language Procedural languages Nonprocedural languages Natural languages Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall10

Development of Program Languages Machine language First-generation language Based on binary numbers The only programming language a computer understands directly Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall11

Development of Program Languages Assembly language A low-level, second-generation language Requires programming individual instructions for each task to be performed by the microprocessor Mnemonics Uses brief abbreviations for program instructions Makes language easier to use than machine language Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall12

Development of Program Languages Procedural languages Third-generation languages Considered high-level languages Do not require programmers to know details relating to the processing of data Easier to read, write, and maintain Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall13

Development of Program Languages Two utility programs that translate code so that the computer can interpret and run programs are: Compilers Translate source code into object code Interpreters Translate source code and execute instructions Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall14

Development of Program Languages Categories of Procedural Language Structured programming languages A solution to spaghetti code Lots of GOTO statements Difficult to follow and prone to errors A set of standards to make programs more readable, reliable, and maintainable Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall15

Development of Program Languages Categories of Procedural Language (continued) Modular programming languages Divide programs into self-contained modules Use information hiding: keeping information about one module secret from authors of other modules Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall16

Development of Program Languages Nonprocedural languages Fourth-generation languages Report generators (database reports) Query languages SQL (structured query language) Doesn’t require programmers to deal with step- by-step procedures to achieve the appropriate programming outcome Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall17

Development of Program Languages Natural language Fifth-generation languages Still being perfected Nonprocedural Use everyday language to program Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall18

Development of Program Languages Object-oriented programming (OOP) Coding is attached to basic prebuilt items called objects, which include: Data Procedures or operations called methods An interface to exchange messages with other objects Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall19

Development of Program Languages Object-oriented programming (OOP) (continued) Makes information hiding or encapsulation a reality Examples of object-oriented programming languages are C++, Java, and Visual Basic.NET Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall20

Development of Program Languages Elements of object-oriented programming Objects: units of computer information Classes: categories of objects Reusability of objects Inheritance: ability to pass on characteristics to subclasses Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall21

Development of Program Languages Rapid application development (RAD) Made possible by object-oriented programming Relies on reusability of objects Joint application development (JAD) Similar to RAD but involves end-user in planning Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall22

Development of Program Languages Advantages of OOP: Allows networked computers to query objects through middleware Does not require code to be changed when data is modified Promotes thinking in a real-world environment, resulting in more effective programs Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall23

A Guide to Programming Languages: One Size Doesn’t Fit All Programmers must select the programming language that can best meets the user’s needs. Two programming languages that have been used since the 1950s are: COBOL (Common Business-Oriented Language) for business applications Fortran (formula translator) for scientific/math/engineering applications Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall24

A Guide to Programming Languages: One Size Doesn’t Fit All Structured and modular languages Required for large-scale program development Examples Ada BASIC Visual Basic Pascal C Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall25

A Guide to Programming Languages: One Size Doesn’t Fit All Object-oriented languages Provide easier programming techniques Examples Smalltalk C++ Java Visual Basic.NET Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall26

A Guide to Programming Languages: One Size Doesn’t Fit All Web-based languages Not considered programming languages Enable the interpretation of both text and objects by browsers Two types: Markup languages Scripting languages Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall27

A Guide to Programming Languages: One Size Doesn’t Fit All Markup languages Define text structure through a set of instructions that are identified with tags. Content lies between tags. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall28

A Guide to Programming Languages: One Size Doesn’t Fit All Types of markup languages include: HTML (Hypertext Markup Language) XML (Extensible Markup Language) XHTML (eXtensible Hypertext Markup Language Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall29

A Guide to Programming Languages: One Size Doesn’t Fit All Scripting languages Use basic programs called scripts to control Web page actions or responses Types of scripting languages include: VBScript JavaScript Visual Studio.NET Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall30

The Program Development Life Cycle Program development life cycle (PDLC) Used to overcome debugging and maintenance problems Made up of six phases, from problem definition through program implementation and maintenance Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall31

The Program Development Life Cycle Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall32