Perl - More on Character Strings

More on Character Strings - Perl module P212

a.k.a. "Regular Expressions, part 2". How to match a string to a pattern, how to extract information from a match, how to repeat matches, to substitute one string of text for another, and how to translate on a character by character basis.

This topic is presented on public courses Perl Programming, Perl bootcamp

Examples from our training material

bindemo	Printing out and reading in binary numbers
cats2	Sample answer 2
catshow	Sample answer 1
favex.pl	Postcode, Zipcode, credit card no. etc - regular expression matches
filler	Using Regular Expressions to "mailmerge"
getlinks	Find all href links from a page
greedyvglobal.pl	Greedy matches v Global matches
html1	Matching HTML - a greedy match doesn't work
html2	Sparse matching, looking for an HTML tag
html3	Global matching in a scalar context
html4	Global matching in a list context
letters	Look for word starting and ending with same letter
n2	Capturing groups into $1 and $2
n3	Capturing groups into a list
n4	Special variables $' $& and $`
n5	$PREMATCH, $MATCH and $POSTMATCH
name	Match and substitute (long winded way!)
name2	Match and substitute - (example that fails)
name3	Match and substitute executed block
names	Regular expression match - revision
ogado	Anagrams of First Great Western served stations
pcv1	Postcode extractor - mark 1
pcv2	Postcode extractor Mk2 - save into named variables
pcv3	Postcode, Mk3 - extract multiple postcodes
phone	Substitution using back reference
pwline	Character by character translation with tr
pwline2	using tr to change multiple characters; also c and s switches
regextra	Splitting up a URL via a regex - sample exercise answer
rogues	Using tr to find invalid characters in a string
sedm	Substitue operator
totext	Converting < > and & to web standard sequences
yem	Perl regular expression - information returned
ystwyth.pl	binary data handling - examine a .gif file

More web pages on this subject

Regular Expressions in Perl

Opentalk forum discussions related to this topic

any option other than substr
Replace block of HTML
Importing a regular expression from a file
Help in regular expression
Extract first 20 words
Apostrophes
sequence file into a numeric file
Regular Expression Help
RegEx in scalar
Finding the latest version number
return part of a string that matches a pattern
how to tokenize in perl
Variable formatting beyond printf
Use of qq to prevent Mysql injection
Say what you mean in regular expressions
Sample Regular Expressions
RegEx
Perl Regex One Liner To Substitute Multiline Text
Language parsing
Help please with Perl regular expressions
HTML code in Perl
Greedy v Global on regular expressions
Finding all matches to a Regular Expression
Editing multiple files

Pictures

Yes!

Background information

Some modules are available for download as a sample of our material or under an Open Training Notes License for free download from http://www.training-notes.co.uk.

Topics covered in this module

Summary to date.
Extracting information from a match.
$1, $2, etc.
Assign to a list.
$`, $& and $Õ.
More about regular expressions.
What else can I put in regular expressions?.
More brackets.
Match modifiers.
Global v Greedy.
Alternative delimiters.
Some favourite regular expressions.
To match an email address.
To match a UK Postcode.
To match an American Zip code.
To match a date (UK Style).
To match a time.
To match a complete URL for a web page.
To match a Visa number.
To match a Mastercard number.
To match a UK Phone number.
To match a UK car registration plate.
To match a UK national insurance number.
To match a book's ISBN number.
Substitutions.
Substitute and execute.
Regular expression efficiency.
tr.
Handling binary text.
Summary.

Course links

The following web pages are used as references / examples in this module

[Link] INACCESSIBLE
(at https://cedar.he.net/internal.html#javabooks)

[Link] Graham Ellis - Home Page
(at http://www.grahamellis.co.uk/index.html)

We check these links from time to time with a spider written in PHP. Latest full check was on Saturday, 12th June 2004. Titles are extracted from the web pages listed.

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