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String Pattern Matching
Pattern matching example from a Well House Consultants training course
More on Pattern matching [link]

This example is described in the following article(s):
   • Lua Regular Expressions - [link]

Source code: stratch Module: U108


info = "Aylesbury Melksham Melksham Melksham Bristol Bristol Melksham"

print ("\nGlobal Substitute")
i2 = string.gsub(info,"Melksham",'"Well House Manor"')
print (i2)
print ("Global Substitute - limited number of replacements")
i3 = string.gsub(i2,"\"Well House Manor\"",'MKM',2)
print (i3)

--[[

Lua uses a pattern matching system that is NOT regular expressions

Reason - "Lua is a small, tight language and a POSIX Regular Expression
engine would have been bigger than the entire string function library"

But is is quite similar ;-)

]]


print ("\nBracket classes - any one of")
i2 = string.gsub(info,"[aeiou]",'VV')
print (i2)
print ("\nFind returns the position of the match")
i2 = string.find(info,"[aeiou]")
print (i2)

--[[
^ means "starting with"
$ means "ending with"

%d means a digit
%a for a letter
%u for an upper case letter
%l for a lower case letter
%% means really match a % character (similar for other specials)

+ means one or more of the previous item
? means zero or 0ne character
* means 0 or more or the previous item
- also means 0 or more of the previous item but is SPARSE
]]


--[[ ----------------- Sample Output

[trainee@easterton u108]$ lua stratch

Global Substitute
Aylesbury "Well House Manor" "Well House Manor" "Well House Manor" Bristol Bristol "Well House Manor"
Global Substitute - limited number of replacements
Aylesbury MKM MKM "Well House Manor" Bristol Bristol "Well House Manor"

Bracket classes - any one of
AylVVsbVVry MVVlkshVVm MVVlkshVVm MVVlkshVVm BrVVstVVl BrVVstVVl MVVlkshVVm

Find returns the position of the match
4
[trainee@easterton u108]$

]]



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.

Other Examples
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.

Other resources
• 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.

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This web site is written and maintained by Well House Consultants.

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.

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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.

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