DAT2322 - Course Notes

Introduction to Computer Programming

Prepared by Maitang Mark
March, 2000

Introduction

  This set of lessons is designed to introduce the fundamental concept of computer programming to students in the School of Business at Algonquin College.

Often, computer programming is seen as a mystical process to students who are beginners to computer discipline, or who are of non-computer-related disciplines. There exists a great challenge for students to comprehend what causes a computer program to behave one way and not the other way.

What is intended here is to demystify the underlying logic behind these computer programs.

The tool selected to facilitate the understanding of the computer programming concept is the Perl language. Only a selected set of Perl commands which conform strictly to the basic structured programming practice are used in these lessons. (See Appendix A for a summary list of Perl commands.)

    The Table of Contents

What is Perl?

  Perl is an acronym for Practical Extraction and Report Language. It is a new and improved script language growing out of many older popular script languages, such as shell scripts, grep, sed, awk, and many more of the UNIX operating system.
        Practical Extraction
        and Report Language    

Why Perl?

    There are many advantages of using Perl as the first programming language.
  For users who are familiar with Microsoft DOS, DOS batch files are simpler examples of script files. Like all script files, Perl does not require complicated compile, link, and execute processes used by the mainstream computer languages, such as COBOL, C, C++, and PASCAL, in order to run it. Students use any text editor, such as Notepad or DOS Edit to compose a Perl program, save it, and ask Perl to run it. WordPerfect or Word can be used too, provided that the Perl program is saved in DOS text mode.
    Script files are easy  
        to work with.    
 
  For many years, Perl has been available on the UNIX system free of charge. UNIX operating systems are what started the Internet revolution. Perl, the same as html and Java, is a language developed specifically for use on the Internet. In other words, it is an e-commerce language. Amazon.com, the leading e-commerce company maintains its web site using Perl.
    Perl is free and is an
    e-commerce language.
 
  Recently, Perl is made available (or is ported) to personal computers such as Macintosh, Windows 95/98/NT with either Intel or Alpha processors. They are also free of charge. (See Appendix A for free download instructions.) The basic Perl package occupies only 5 megabytes of hard disk space. A full set of manuals accompanying the package takes another 3 or more megabytes depending on the versions.
    Perl is cross-platform.
      It has a low
        hardware cost.
 

Q. If Perl is such a great language, why aren't more people using it?

It is a new script language and most of the Perl books are published with UNIX users in mind as it originated from the UNIX operating system. Only recently is it available to PC users. It has yet to develop a group of knowledgeable followers. The spread of the Internet and emergence of e-commerce applications in the last 12 months brought to focus the advantages of using Perl.

Do you know DOS?

Students need to know some DOS in order to work with Perl. The Windows version of Perl operates in the DOS command mode. It is necessary to work in the MS-DOS mode in the Windows 95/98 environment. It would be helpful if the student has knowledge of a few simple DOS commands and tasks such as:
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M. Mark, 2000.03.04 | Introduction | Lesson 1 | Lesson 2 | Lesson 3 | Lesson 4 | Appendix |