Variable Search

Hey Coder's
I have a problem for my new program, because I dosn't found a way to do that what I want. Maybe one of you can code it.
I have a few variables they are all standing for a item ID. So maybe they are going so L1 to L64, M1 to M64 and R1 to R64. So now I will look with a function in what variable my item is. So I will type the number and found the Variable with the number. How can I make the function? Hope someone can help me.
Thanks a lot,
Timia2109

P.S sorry for bad English :/

You should store all your variables in table to make is easy (it's possible to store those in variables, but this is advanced Lua).

Example

Spoiler

-- Create table
local items = {}
--Let's put stone ID at index "stone"
items['stone'] = 1
--And torch at 50
items['torch']= 50
-- Searching function
local function search(table, toSearch)
-- Check if given table is actually table
if type(table) ~= "table" then
  -- If it's not, raise error
  error("Table expected, got "..type(table) or "nil", 2)
end

-- Loop trough all values in given table
-- Set "index" to current item's index and set "value" to current item's value
for index, value in pairs(table) do
  -- If we fount it
  if index == toSearch then
   -- Return fount value
   return value
  end
end

-- If we reached this point it meas that items was not fount
-- Return false since nothing was fount
return false
end
-- Some testing
-- Search for "stone" in table "items"
print(tostring(search(items, "stone"))) --> 1
print(tostring(search(items, "noSuchThing"))) --> false
-- Search inside nil
search(nil, "stone")

Better syntax highlighting: pastebin

Ok a big thank's to you! I think I have understand it!
But there is question that have got now. How can I save and load tables in a file? How I can do that with a variable I know, but how can I make it so?

Thanks again,
Timia2109

Cool! :D/>

timia2109, on 30 July 2013 - 10:36 AM said:

Ok a big thank's to you! I think I have understand it!
But there is question that have got now. How can I save and load tables in a file? How I can do that with a variable I know, but how can I make it so?

Thanks again,
Timia2109

Would this be useful? .-.

nTable = {}

-- Writing table to file
function wTable(filename,nTable)
 file = fs.open(filename,"w")
  file.writeLine(textutils.serialize(nTable)
 file.close()
end

-- Reading tables from files
function rTable(filename)
  file = fs.open(filename,"r")
  nTable = textutils.unserialize(file.readAll())
 file.close()
 return nTable
end

jesusthekiller, on 30 July 2013 - 07:06 AM said:

-snip-

This works perfectly well and is simple. However, we can actually speed the search up quite a bit using the indexes.

For example:

local tItems = {
  ["torch"] = 50;
  ["stone"] = 1;
  ["cobblestone"] = 4;
}

local function search(item)
  return tItems[item]
end

print(search("cobblestone")) --#Prints out 4
print(search("torch")) --#Prints out 5
print(search("batman")) --#Prints out nothing because batman is not an item

Hell blazes, how could I not think about it :P/>

A big thanks goes to you all! I don't know the table function until now. I be so happy, that I now can make my program now. Thanks a lot to you all!

You can also do it with this function, but I highly suggest to use a table.

local function getVar( varName )
    if type( varName ) ~= "string" then error( "String expected, got " .. type( varName ), 2 ) end
    local env = getfenv( 1 )
    if env[varName] then
      return env[varName]
    end
    return nil
end

x = 5

print( getVar("x") )

However with this way you cannot declare your variables locally.

instead of env use _G

jesusthekiller, on 30 July 2013 - 06:43 PM said:

instead of env use _G

The variable doesnt get into the _G table. Only in the environment of the program itself.

Oh? Didn't knew that :P/>

Hey Guys,
thank you for show me the table function it's so helpful, but a question again.

Today I found this

Spoiler

local FileList = fs.list("")
for _, file in ipairs(FileList) do
  print(file)
end

and now the question. How can I take from the table, the count of the files and how can I read one of the elements like file1, file2…?

Thanks,
timia2109

timia2109, on 03 August 2013 - 11:31 AM said:

-snip-

So essentially you want a way to count the number of files in a folder?

Pretty simple, just use the # operator on the table returned by fs.list
Example:

local fileList = fs.list("/rom/programs")
print("The number of files in rom/programs is: " .. #fileList)

To get the names of the files, all you have to do is use a loop.
Example:

local fileList = fs.list("/rom/programs")
for index, fileName in ipairs(fileList) do
  print("File: " .. fileName)
end

This would print out the name of every file/folder inside of rom/programs.