string.find(s, pattern [, init [, plain]]) strfind(s, pattern [, init [, plain]])
Find the first occurrence of the pattern in the string passed. If an instance of the pattern is found a pair of values representing the start and end of the string is returned. If the pattern cannot be found nil is returned.
> = string.find("Hello Lua user", "Lua")
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> = string.find("Hello Lua user", "banana")
nil
We can optionally specify where to start the search with a third argument. The argument may also be negative which means we count back from the end of the string and start the search.
> = string.find("Hello Lua user", "Lua", 1) -- start at first character
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> = string.find("Hello Lua user", "Lua", 8) -- "Lua" not found again after character 8
nil
> = string.find("Hello Lua user", "e", -5) -- first "e" 5 characters from the end
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The pattern argument can be a regular expression which allows more complex searches. See the Patterns Tutorial on Lua-Users.org and Pattern matching for more information. We can turn off the regular expression feature by using the optional fourth argument plain. plain takes a boolean value and must be preceded by init. E.g.,
> = string.find("Hello Lua user", "%su") -- find a space character followed by "u"
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> = string.find("Hello Lua user", "%su", 1, true) -- turn on plain searches, now not found
nil
Example
Sometimes it's more appropriate to use string.find, rather than string.gmatch, eg:
local msg = "Phase2:- There isn't any need for iterating over this mini-string."; local startPos, endPos, firstWord, restOfString = string.find( msg, "(%w+)[%s%p]*(.*)");
Result
startPos = 1 endPos = 66 firstWord = "Phase2" restOfString = "There isn't any need for iterating over this mini-string."