Perl Cookbook

Chapter 1. Strings

Introduction

He multiplieth words without knowledge.

—Job 35:16

Many programming languages force you to work at an uncomfortably low level. You think in lines, but your language wants you to deal with pointers. You think in strings, but it wants you to deal with bytes. Such a language can drive you to distraction. Don’t despair, though—Perl isn’t a low-level language; lines and strings are easy to handle.

Perl was designed for text manipulation. In fact, Perl can manipulate text in so many ways that they can’t all be described in one chapter. Check out other chapters for recipes on text processing. In particular, see Chapter 6, and Chapter 8, which discuss interesting techniques not covered here.

Perl’s fundamental unit for working with data is the scalar, that is, single values stored in single (scalar) variables. Scalar variables hold strings, numbers, and references. Array and hash variables hold lists or associations of scalars, respectively. References are used for referring to other values indirectly, not unlike pointers in low-level languages. Numbers are usually stored in your machine’s double-precision floating-point notation. Strings in Perl may be of any length (within the limits of your machine’s virtual memory) and contain any data you care to put there—even binary data containing null bytes.

A string is not an array of bytes: You cannot use array subscripting on a string to address one of its characters; use substr for that. Like all data types in ...