Pattern matching - SLOW code
Pattern matching example from a Well House Consultants training course
More on Pattern matching [link]
Source code: slander0 Module: U108
--[[ This is a pattern matching example that goes through
a data file of 43 Mbytes and finds all log file records which
are Google search engine arrivals.
In this (the slower of two example), I have used a single match
and it turns out to be 1000 times slower than a doing a series
of matches. ]]
fh = io.open("ac_short")
running = true
mcount = 0
count = 0
while running do
line = fh:read()
if line ~= nil then
count = count + 1
n,m,ip,query = string.find(line,'(%S+).*"http.*%.google%..*[&?]q=(.-)[&"]')
if n ~= nil then
mcount = mcount + 1
if query ~= nil then
running = false
taken = os.clock()
print ("time taken in seconds - ",taken)
Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Lua
* Lua Programming
* Lua Programming
Also available on on site courses for larger groups
Books covering this topic
Yes. We have over 700 books in our library. Books covering Lua are listed here and when you've selected a relevant book we'll link you on to Amazon to order.
This example comes from our "Pattern matching" training module. You'll find a description of the topic and some other closely related examples on the "Pattern matching" module index page.
Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.
Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
• The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.
Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.
Web site author
This web site is written and maintained by Well House Consultants.
Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.
This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.
Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.
PH: 01144 1225 708225 • EMAIL: email@example.com • WEB: http://www.wellho.net • SKYPE: wellho
PAGE: http://www.wellho.net/resources/ex.php • PAGE BUILT: Sun Oct 11 14:50:09 2020 • BUILD SYSTEM: JelliaJamb