# Strings and Sorting

### Finding a Substring with index

Finding a substring depends on where you have lost it. If you happen to have lost it within a bigger string, you』re in luck because the index function can help you out. Here』s how it … Read the rest

# Directory Operations

### Moving Around the Directory Tree

Your program runs with a 「working directory,」 which is the starting point for relative pathnames. That is, if you refer to the file fred, that means fred in the current working directory.

The chdir … Read the rest

# File Tests

### File Test Operators

Before we start a program that creates a new file, let』s make sure that the file doesn』t already exist so that we don』t accidentally overwrite a vital spreadsheet datafile or that important birthday calendar. For this, we … Read the rest

# Perl Modules

There is a lot more to Perl than what we』re able to show you in this book, and there are a lot of people doing a lot of interesting things with Perl. If there is a problem to solve, then … Read the rest

# More Control Structures

### The unless Control Structure

In an if control structure, the block of code is executed only when the conditional expression is true. If you want to execute a block of code only when the conditional is false, change … Read the rest

# Processing Text with Regular Expressions

### Substitutions with s///

If you think of the m// pattern match as being like your word processor』s 「search」 feature, the 「search and replace」 feature would be Perl』s s/// substitution operator. This simply replaces whatever part of a variable matches a … Read the rest

# Matching with Regular Expression

### Matches with m//

We』ve been writing patterns in pairs of forward slashes, like /fred/. But this is actually a shortcut for the m// (pattern match) operator. As you saw with the qw// operator, you may choose any pair of … Read the rest