RegexBuddy: Learn, Create, Understand, Test, Use and Save Regular Expression Perl Regular Expressions by Example Introduction Regular expressions are very powerful tools for matching, searching, and replacing text. Unfortunately, they are also very obtuse. It does not help that most explanations of regular expressions start from the specification, which is like learning to love Friends reruns by reading a VCR manual. This page provides some simple examples for reference. You should know a little programming and how to run basic perl scripts before reading this article. Section 1: Basic matching and substitution Declare a local variable called $mystring. my $mystring; Assign a value (string literal) to the variable. $mystring = "Hello world!" Does the string contains the word "World"? if($mystring =~ m/World/) { print "Yes"; } No, it doesn't. Does the string contains the word "World", ignoring case? if($mystring =~ m/World/i) { print "Yes"; } Yes, it does. I want "Hello world!" $mystring =~ s/world/mom/; print $mystring; Prints "Hello mom!". Now change "Hello mom!" Okay, ignoring case, change "Hello mom!" *?
Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns Perl programming documentation Advanced Regular Expression Tips and Techniques Twice a month, we revisit some of our readers’ favorite posts from throughout the history of Nettuts+. Regular Expressions are the Swiss Army knife for searching through information for certain patterns. They have a wide arsenal of tools, some of which often go undiscovered or underutilized. Adding Comments Sometimes, regular expressions can become complex and unreadable. For example, here is something we might use to check for US phone numbers. It can become much more readable with comments and some extra spacing. Let's put it within a code segment. The trick is to use the 'x' modifier at the end of the regular expression. Using Callbacks In PHP preg_replace_callback() can be used to add callback functionality to regular expression replacements. Sometimes you need to do multiple replacements. Let's look at this example, where we have an e-mail template. Notice that each replacement has something in common. So here is the better way of doing this with callbacks: Greedy vs. Filtering Patterns
retut <div class="noscript"><p><strong>Please note: Many features of this site require JavaScript. You appear to have JavaScript disabled, or are running a non-JavaScript capable web browser.</strong></p><p> To get the best experience, please enable JavaScript or download a modern web browser such as <a href=" Explorer 8</a>, <a href=" <a href=" or <a href=" Chrome</a>. </p></div> perlretut - Perl regular expressions tutorial This page provides a basic tutorial on understanding, creating and using regular expressions in Perl. Perl is widely renowned for excellence in text processing, and regular expressions are one of the big factors behind this fame. What is a regular expression? A note: to save time, 'regular expression' is often abbreviated as regexp or regex. "#!
Using Regular Expressions in PHP and JavaScript - O'Reilly Answers Using Regular Expressions in PHP and JavascriptBy Robin Nixon (O'Reilly page | Amazon page) Regular expressions are supported by both Javascript and PHP, as well as a number of other languages. They make it possible to construct the most powerful of pattern-matching algorithms within a single expression. Every regular expression must be enclosed in slashes. Matching through metacharacters Let’s say you’re looking for the name “Le Guin” and know that someone might spell it with or without a space. The difficulty of classifying Le Guin’s works So you need to match “LeGuin,” as well as “Le” and “Guin” separated by any number of spaces. /Le *Guin/ There’s a lot more than the name “Le Guin” in the line, but that’s OK. Suppose that you know there is always at least one space. /Le +Guin/ Fuzzy character matching The dot (.) is particularly useful, because it can match anything except a newline. Unfortunately, the plus sign keeps on matching up to the last > on the line, so you might end up with: /\d/
Regex Powertoy (interactive regular expressions) regexxer Search Tool Regular Expressions - a Simple User Guide A Regular Expression is the term used to describe a codified method of searching invented, or defined, by the American mathematician Stephen Kleene. The syntax (language format) described on this page is compliant with extended regular expressions (EREs) defined in IEEE POSIX 1003.2 (Section 2.8). EREs are now commonly supported by Apache, PERL, PHP4, Javascript 1.3+, MS Visual Studio, most visual editors, vi, emac, the GNU family of tools (including grep, awk and sed) as well as many others. Extended Regular Expressions (EREs) will support Basic Regular Expressions (BREs are essentially a subset of EREs). Most applications, utilities and laguages that implement RE's, especially PERL, extend the ERE capabilities and what are typically called PERL Compatible Regular Expressions (PCREs) have, largely, become a de facto standard. Implementation documentation should always be consulted in case some wierd Regular Expression variant is involved. Contents The title is deceptive. Simple Matching