11 replies to this topic

[Konlab]

Help me with file formats, how can I detect for example .bmp ending filename?
Other can I do, but the endings are problems.
Sorry for bad english

[apemanzilla]

Assuming you already have the filename:

function getExtension(filename)
  if filename:find("$.+(%..+)^") then
    local a,b,c = filename:find("$.+(%..+)^")
    return c
  end
end

[Konlab]

Sorry, I don't understand anything.
Please tell me what line what does.

[Agoldfish]

Konlab, on 16 May 2014 - 07:58 PM, said:

Sorry, I don't understand anything.
Please tell me what line what does.

It detects everything after a period in a file name.

[Konlab]

And why $.+(%..+)
.?

[Lignum]

Konlab, on 16 May 2014 - 08:01 PM, said:

And why $.+(%..+)
.?

It's a pattern.

[Konlab]

Uh
if IDon'tUnderstandAnything() then
print("go away")
else
print("stay here")
end
Output:
go away

[apemanzilla]

Alright. I'll break it down:
The ": starts a string, as patterns are strings.
The $: means that the string must START with the following pattern
The .: matches any character
The +: allows the previous case to be repeated (match any characters.
The %.: matches for a REAL period
The (: starts a capture (an additional return value if the containing case was matched)
The .+ again, matches all characters
The ): closes the capture
The ^: means the string must END with this pattern.

In short it looks for something like this:
(Any text).(any text) and returns the second set of parenthasees's contents.

[Lignum]

apemanzilla, on 16 May 2014 - 08:42 PM, said:

The $: means that the string must START with the following pattern.
The ^: means the string must END with this pattern.

Are you sure it's not the other way around? Because your code only seems to work for me when I swap the two.

Your code could also be shortened to a one-liner:

function getExtension(filename)
  return filename:match("^.+(%..+)$")
end

[Konlab]

And what is filename:find

[KingofGamesYami]

Konlab, on 17 May 2014 - 05:56 AM, said:

And what is filename:find

http://lua-users.org...LibraryTutorial

[TyDoesMC]

You need to stop complaining about our answers and read up on lua.