LOCAL foilset Introduction to Web Technologies -- ECS400 Course Overview

Given by Nancy J. McCracken at ECS400 Senior Undergraduate Course on Spring Semester 1996. Foils prepared 27 February 1996
Abstract * Foil Index for this file

See also color GIF

• Text: Learning PERL (the Llama book), Randal L. Schwartz, OšReilly & Associates, 1993.
• PERL4 is an interpreted language that can be regarded as a cross between C, Unix shell, sed and awk. It is a C-based language which can also deal directly with Unix commands and file system and easily do string processing matching.
• In this course, we will concentrate not on using PERL in systems programming, but in using PERL for CGI programming, i.e. implementing programs activated from Web pages.
• In general, we use PERL for tedious high level things which can take a long time to program but not much execution time. For computationally intense programs, we would use a compiled language such as C.
• Our first lecture on Perl will show a series of small programming examples from Chapter 1 of the Learning Perl book, designed to illustrate the main features of the language. Later we will cover each topic in more detail.

This table of Contents Abstract

Foil 1 Introduction to PERL Programming:
a Stroll Through Perl
from \"Learning Perl\" by Randal L. Schwartz

• Nancy McCracken
• NPAC
• Syracuse University
• 111 College Place
• Syracuse NY 13244-4100
• February 5, 1996
• Click here for body text

Foil 2 PERL4

• Text: Learning PERL (the Llama book), Randal L. Schwartz, OšReilly & Associates, 1993.
• PERL4 is an interpreted language that can be regarded as a cross between C, Unix shell, sed and awk. It is a C-based language which can also deal directly with Unix commands and file system and easily do string processing matching.
• In this course, we will concentrate not on using PERL in systems programming, but in using PERL for CGI programming, i.e. implementing programs activated from Web pages.
• In general, we use PERL for tedious high level things which can take a long time to program but not much execution time. For computationally intense programs, we would use a compiled language such as C.
• Our first lecture on Perl will show a series of small programming examples from Chapter 1 of the Learning Perl book, designed to illustrate the main features of the language. Later we will cover each topic in more detail.

Foil 3 The Simplest Program: Hello, World!

• Each Perl program is in a Unix file, with executable permission, and is executed by typing the name of the file as a command.

Foil 4 Scalar Variables and Keyboard Input

• This program uses a scalar variable, which always starts with a $, prompts for input, reads the name, and prints hello.

Foil 5 Conditional and Comparison

• This program prints a special greeting for Randal, and an ordinary one for everybody else.

Foil 6 While Loop

• This program asks everyone, except for Randal, for a secret password.

Foil 7 Arrays, also known as lists

• This program uses an array variable, which must start with @, to hold several secret passwords.

Foil 8 Associative arrays

• Associative arrays, variables start with %, are tables with keywords and values and are used here to give each person their own password.

Foil 9 Regular Expressions and String Matching

• Accept input name in varying formats by matching strings that are case insensitive and longer, such as Randal L. Schwartz

Foil 10 Substitute and Translate Operators

• Truncate all input names to the first name and translate to all lower case.

Foil 11 Subroutines

• All subroutines in Perl have parameters and return a result, the value of the last expression before the return. Undeclared names refer to names in the outer program (global). The subroutine is called with &, for example &good_word($name,$guess);

Foil 12 Reading Files

• A file (or I/O channel) is referred to by a "filehandle". (Perl automatically creates filehandles STDIN, STDOUT and STDERR.) We choose to keep our password table in a file with one word per line, alternating keys and values.

Foil 13 Sending commands to the operating system

• If the wrong person guesses a password, we can send a mail message by issuing the mail command. The pipe symbol is used in the file name to indicate a command.

Foil 14 Formatting output and using file names

• A format statement can be associated with each file handle and used for writing to that channel. The format name is the name of the file handle - there can can also be another special format for labelling the tops of output pages.

Foil 15 Further Topics

• Further examples in Chapter 1 of Learning Pearl discuss
  • renaming files
  • keeping an associative table in a file database
• Final programs are on page 32.

Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu