Programming Perl in UNIX

Course Number : CIT 370

Week 3

Prof. Daniel Chen

Introduction

Review and Overviews Chapters 5 and 6 Summary Lab Quiz 1 Next Week (Week 4)

Topics of Discussion About Perl Operators Mixing Data Types Precedence and Associativity Control Structures, Blocks, and

Compound Statements Decision Making – Conditional

Constructs Loops

Chapter 5: Where’s the Operators?

5.1 About Perl Operators 5.2 Mixing Data Types 5.3 Precedence and Associativity

5.1 About Perl Operators

An operator manipulates data objects called operands.

5.2 Mixing Date Types Data Conversion (overloading)

How Strings Are Converted to Numbers Table 5.1

5.3 Precedence and Associativity Precedence refers to the way is which the operator

binds to its operand.

Associativity refers to the order in which an operator evaluates its operands: left to right, or right to left. Table 5.2

Assignment Operators Table 5.3

Relational Operators Table 5.4

5.3.3 Equality Operators Numeric

Table 5.6

String Table 5.7

5.3.4 Logical Operators Unless C, the short-circuit operators do not return

0 (false) or 1 (true), but rather the value of the last operand evaluated. Table 5.8

Logical Word Operators (and, or , xor) These logical word operators are of lower

precedence than the short-circuit operators, but work the same way.

5.3.6 Arithmetic Operators

Table 5.9

Autoincrement and autodecrement operators Table 5.10

Other Operators Bitwise Logical Operators

TABLE 5.12 & Table 5.13

Conditional Operators Format: conditional expression ? expression :

expression

Range Operator

Special String Operators and Functions Table 5.14

Generating Random Numbers The rand/srand Functions

Chapter 6: If Only, Unconditionally, Forever

6.1 Control Structures, Blocks, and Compound Statements

6.2 Decision Making – Conditional Constructs

6.3 Loops

Control Structures, Blocks, and Compound Statements The decision-making constructs (if, if/else,

if/elsif/else, unless, etc.) contains a control expression that determines whether a block of statements will be executes.

The looping constructs (while, for, foreach) allow the program to repetitively execute a statement block until some condition is satisfied.

A compound statement or block consists of a group of statements surrounded by curly braces.

Unlike C, Perl requires curly braces even one statement when that statement comes after the if, else, while, etc.

Decision Making-Conditions Constructors if and unless Statements

The if Construct

The if/else Construct

The if/elseif/else Construct

The unless Construct

Loops The while loop

The until loop

The do/while and do/until Loops

The for Loop

The foreach Loop

Loop Control labels

next (continue)

last (break)

redo -it restarts the block without evaluating the loop expression again

goto

A Labeled Block Without a Loop

Nested Loops and Labels

The continue Block

The Phoney Switch Statement

Summary About Perl Operators Mixing Data Types Precedence and Associativity Control Structures, Blocks, and

Compound Statements Decision Making – Conditional

Constructs Loops

Lab

Examples 5.1 – 5.22 (P 101 – 129) Examples 6.1 - 6.24 (P 133 - 161) Homework 3

Quiz 1 Quiz Date: Today

Quiz Time: 11:00 AM - 11:30 AM

Contents: Chapter 1- Chapter 4

No books, no notes, no computer

Next Week

Reading assignment (Textbook chapter 7 and Chapter 8)