Who Should Read This Book?
No previous programming experience is required for you to learn everything you need to
know about programming with Perl from this book. In particular, no knowledge of the C
programming language is required. If you are familiar with other programming
languages, learning Perl will be a snap. The only assumption this book does make is that
you are familiar with the basics of using the UNIX operating system.
Special Features of This Book
This book contains some special elements that help you understand Perl features and
concepts as they are introduced:
l Syntax boxes
l DO/DON'T boxes
l Notes
l Warnings
l Tips
Syntax boxes explain some of the more complicated features of Perl, such as the control
structures. Each syntax box consists of a formal definition of the feature followed by
an explanation of the elements of the feature. Here is an example of a syntax box:
The syntax of the for statement is
for (expr1; expr2; expr3) {
statement_block
}
expr1 is the loop initializer. It is evaluated only once, before the start of the loop.
expr2 is the conditional expression that terminates the loop. The conditional expression
in expr2 behaves just like the ones in while and if statements: If its value is zero, the
loop is terminated, and if its value is nonzero, the loop is executed.
statement_block is the collection of statements that is executed if (and when) expr2 has
a nonzero value.
expr3 is executed once per iteration of the loop, and is executed after the last
statement in statement_block is executed.