The process of looking to see if the pattern occurs in the string is called matching, and the "=~" operator along with the m// tell Perl to try to match the pattern against the string. The portion enclosed in '/' characters denotes the characteristic we are looking for. The value of this expression will be TRUE if $var contains that sequence of characters anywhere within it, and FALSE otherwise. Suppose we want to determine if the text in variable, $var contains the sequence of characters m u s h r o o m (blanks added for legibility). Biologists often use Perl to look for patterns in long DNA sequences. The string is most often some text, such as a line, sentence, web page, or even a whole book, but it doesn't have to be. What is a regular expression? At its most basic, a regular expression is a template that is used to determine if a string has certain characteristics. Mastering even the basics of regular expressions will allow you to manipulate text with surprising ease. Perl regular expressions display an efficiency and flexibility unknown in most other computer languages. Perl is widely renowned for excellence in text processing, and regular expressions are one of the big factors behind this fame. Regular expressions are an integral part of the m//, s///, qr// and split operators and so this tutorial also overlaps with "Regexp Quote-Like Operators" in perlop and "split" in perlfunc. It serves as a complement to the reference page on regular expressions perlre.
This page provides a basic tutorial on understanding, creating and using regular expressions in Perl. Perlretut - Perl regular expressions tutorial #DESCRIPTION
#Regular expression not match perl qr code#
A bit of magic: executing Perl code in a regular expression.
Embedding comments and modifiers in a regular expression.Composing regular expressions at runtime.Compiling and saving regular expressions.More on characters, strings, and character classes.Grouping things and hierarchical matching.