Understanding Computers Ch. 131 Chapter 13 Program Development and Programming Languages.

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Chapter 13

Program Development and Programming Languages

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Overview

This chapter covers:

The program development life cycle (PDLC)

Tools that can facilitate program development

Programming languages

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The Program Development Life Cycle (PDLC)

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Problem Analysis

Purpose: Review the specifications developed during system design and develop program specifications.

Usually performed by systems analyst and programmer.

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

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Program Design Purpose: To determine the algorithms to be used with the final

program.

Approaches to program design:

Structured programming Structures the program

Object-oriented programming (OOP) Groups program components

Aspect-oriented programming (AOP) Re-uses program components

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Program design tools:

Structure charts

Program flowcharts

Pseudocode

Data modeling

Program Design, Cont’d.

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Program Design, Cont’d.

Control structures—patterns that control when and how the instructions in a computer program are performed.

Sequence

Selection (if-then-else, case)

Repetition (do-while, do-until)

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Program Design, Cont’d. Good program design

Be specific.

One-entry-point, one-exit-point rule.

No infinite loops or logic errors.

Documentation: Design specifications (expressed using flowcharts, pseudocode, structure charts, data models, etc.).

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Program Coding

Coding—the process of writing the actual programming steps using a programming language.

Factors involved when choosing a programming

language:

Suitability Integration Standards

Programmer availability Portability Development speed

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Program Coding, Cont’d.

Coding standards—list of rules designed to standardize programming styles.

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Program Coding, Cont’d. Reusable code

Data dictionary

Translating coded programs into executable code Compilers Interpreters Assemblers

Documentation: Documented, executable source code.

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Program Debugging and Testing Debugging—the process of making sure a program

is free of errors.

Preliminary debugging

Syntax errors (typos, wrong syntax, etc.).

Logic errors (wrong formulas, wrong relational operators, etc.).

Dummy print statements can help locate errors.

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Program Debugging and Testing Testing

Alpha testing (inside organization)

Beta testing (outside testers)

Documentation: Completed program package.

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Program Maintenance Program maintenance—the process of updating

software so that it continues to be useful.

Software updates

Software revisions

Made easier by good coding standards, data dictionaries, reusable code, etc.

Documentation: Amended program package.

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Tools for Facilitating Program Development Application generators:

Macro recorders

Report and form generators

Code generators

Computer-aided software engineering (CASE)

Software-asset management tools

Rapid application development (RAD)

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Programming Languages

Programming language—a set of rules used to write instructions to the computer.

Categories of programming languages:

Low-level languages (machine and assembly language).

High-level languages (BASIC, COBOL, C++, etc.).

Very-high-level (fourth-generation languages).

Natural and visual languages.

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Popular Programming Languages

FORTRAN—the oldest high-level programming language; designed for scientific and mathematical applications.

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Popular Programming Languages, Cont’d. COBOL—designed for business transaction

processing.

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Popular Programming Languages, Cont’d. Pascal—designed to teach structured programming;

useful for math and science applications.

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Popular Programming Languages, Cont’d. BASIC—an easy-to-learn beginner’s programming language.

Visual Basic—an object-oriented, fourth-generation version of BASIC.

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Popular Programming Languages, Cont’d.

C, C++, C#—versions of the highly efficient C programming language; C++ and C# are object-oriented.

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Popular Programming Languages, Cont’d.

Java—object-oriented programming language commonly used for Web applications. Platform independence—Java programs can run on any

platform that supports the Java Virtual Machine.

Java applets—concise stand-alone Java applications ready to be inserted into Web pages. Class files Parameters

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Popular Programming Languages, Cont’d.

Other high-level languages:

Ada APL LISP Logo

PL/1 Prolog RPG SmallTalk

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Summary

The program development life cycle (PDLC)

Good program design

Basic control structures

Coding, debugging, maintaining, and documenting programs

Tools that facilitate the program development process

Common programming languages