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stringlualua-patterns

Lua string.gsub text between pattern

How would I extract in Lua a text between a pattern. For example 

s="this is a test string. <!2014-05-03 23:12:08!> something more"
  1. I would need only the date/time as result: 2014-05-03 23:12:08
    print(string.gsub(s, "%<!.-%!>")) doesn't work
  2. I would need all the text WITHOUT the date/time like: "this is a test string. something more"
Solution

  • The pattern "<!.-!>" works, but you need to use string.match to get the date/time part:

     print(string.match(s, "<!(.-)!>"))

    Note that you don't need to escape ! or < in a pattern. Of course escaping them is not an error.

    To get the string without the date/time part, replace it with an empty string:

    local result = string.gsub(s, "<!.-!>", "")
print(result)

    You can also expand the pattern .- to validate the format of date/time more:

    result = string.gsub(s, "<!%d%d%d%d%-%d%d%-%d%d%s+%d%d:%d%d:%d%d!>", "")