Chapter 14

Programming andLanguages

McGraw-Hill/Irwin Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved.

Competencies (Page 1 of 2)

 •Describe the six stepsof programming

 •Discuss design toolsincluding top-downdesign, pseudocode,

flowcharts, and logicstructures

 •Describe programtesting and the tools for

finding and removingerrors

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Competencies (Page 2 of 2)

 •Describe CASE tools and object-orientedsoftware development

 •Explain the five generations of programminglanguages

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Introduction

In this chapter programming is described in twoparts...

• The steps in the programming process

• Some of the programming languages available

Programming is part of Phase 4, SystemsDevelopment, in the Systems Life Cycle.

Competent end users need to understand therelationship between systems development andprogramming.

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Programs and Programming

•  What is a Program?–  A program is a list of instructions

–  Code, Application

–  Programmer, Hacker

•  A problem-solving procedure  –A list of instructions

Prewritten

Custom-written

Application software

System software

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What is Programming?

Programming is software development

Six step procedureProgram specification

Program design

Program code

 – Program test

Program documentation

Program maintenance

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Step 1: Program Specification

Also called programs definition or programanalysis

5 Step ProcessProgram Objectives

Desired Output

 – Input Data

Processing Requirements

Document Program Specifications

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Program Objectives

•  Objectives are the problems that you aretrying to solve

•  Programming requires a clear statement ofthe problem that you are looking to address

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Program Specification StepsContinued

•  Desired output

•  Input Data

•  ProcessingRequirements

•  ProgramSpecifications

End user’s sketch ofdesired output

Document

Example of statement of

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hours worked 14-9

Step 2: Program Design

 •Plan a solution

•  Use structured programming techniques–  Top-down program design

–  Pseudocode

 –Flowcharts

–  Logic structures

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Top-Down Program Design

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PseudocodeSummarizes the logic for a program.

Informal list of instructions.

Like a program, but written in English words.

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Flowchart

Flowchart symbols

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Flowchart example14-13

Logic Structures

•  Sequence structure

•  Selection structure

•  Loop structure

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Step 3: Program Code

•  Writing the program or coding•  The good program

 –Reliable–  Catch input errors–  Understandable to otherprogrammers–  Structured programs best method

 –Use the most appropriatecomputer language

•  Coding

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Coding

•  Formatting or presentation language

•  Programming language

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Common ProgrammingLanguages

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C

C++

Java

Python, Perl

Visual Basic–  Basic

•  Fortran – Older, for numerical

•  Cobol – Older, for transaction processing systems (TPS)

•  Assembler ( = machine language)

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Step 4: Program Test

 •Debugging  –Testing

 –Eliminating errors

 •Syntax errors

 •Logic errors

 •Testing process

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Types of Testing

•  Desk checking – sit and look at it

•  Manual testing – try specific data values

•  Translation – try to “compile” i–  This catches syntax errors

•  Run the program–  Testing on sample data

•  Beta testing–  Give preliminary version to a few brave users

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Step 5: Program Documentation

•  Written descriptions and procedures about aprogram

•  Important for people who will use theprogram–  Users

 –Operators

 –Programmers

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Step 6: Program Maintenance

75% of total lifetime cost

Error-free operations

Effective program

Two categories–  Operations

–  Changing needs

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Case Tools

 •Computer-aided software engineering(CASE)

–  Automate development process•  Designing

•  Coding

•  Testing activities

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Object-Oriented SoftwareDevelopment

•  Focuses less on procedures, more on

relationship between objects

•  OOP: Object-oriented programming

•  Object contains both the data and the

processing operations

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Generations of ProgrammingLanguages (Page 1 of 2)

•  Occurring in “generations” or “levels”–  Levels-Machine languages to natural languages

•  There are five generations :–  Lower level closer to machine language–  Higher level closer to human-like language

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Generations of ProgrammingLanguages (Page 2 of 2)

1st -- Machine languages

2nd -- Assembly languages

3rd -- High level procedural languages )3GL(

4th -- Problem-Oriented languages )4GL(

5th -- Natural Languages & Visualprogramming languages )5GL(

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