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

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* Learning to program in Lua
* Lua Programming
* Lua Programming
Also available on on site courses for larger groups

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