How to check if matching text is found in a string

Question

I need to make a conditional that is true if a particular matching text is found at least once in a string of text, e.g.:

str = "This is some text containing the word tiger."
if string.match(str, "tiger") then
    print ("The word tiger was found.")
else
    print ("The word tiger was not found.")

How can I check if the text is found somewhere in the string?

Answer 1

You can use either of string.match or string.find. I personally use string.find() myself. Also, you need to specify end of your if-else statement. So, the actual code will be like:

str = "This is some text containing the word tiger."
if string.match(str, "tiger") then
  print ("The word tiger was found.")
else
  print ("The word tiger was not found.")
end

or

str = "This is some text containing the word tiger."
if string.find(str, "tiger") then
  print ("The word tiger was found.")
else
  print ("The word tiger was not found.")
end

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It should be noted that when trying to match special characters (such as .()[]+- etc.), they should be escaped in the patterns using a % character. Therefore, to match, for eg. tiger(, the call would be:

str:find "tiger%("

More information on patterns can be checked at Lua-Users wiki or SO's Documentation sections.