[Solved] attempt to concatenate string and nil

shell.run("clear")
print("Lazuli Azure Resort and Spa")
print("---------------------------")
print(" ")
function pickRoom()
  room = {101, 102, 103, 201, 202}
  a = math.random(0,4)
  numbRoom = tonumber(room[a])
  dir = "rooms/"..numbRoom -- LINE 10
  h = fs.open(dir, "r")
  if h == "true" then
	shell.run("clear")
	print("Your room number is "..numbRoom..".")
	local g = read()
	h = fs.open(dir, "w")
	h.write("false")
	h.close()
	pickroom()
  else
	pickRoom()
  end
end
pickRoom()

KingofGamesYami, on 06 July 2017 - 05:58 AM said:

Well, it's not the fs API. That won't throw that particular error. "concatenate" refers to the joining of two strings (the .. operator).

I'd say for whatever reason numbRoom is nil. Probably a misspelling, check lines 9 and 10. (You also appear to have a misspelling later, calling "pickroom" not "pickRoom")

—–
I'd also like to point out that this function is endlessly-recursive which will lead to problems. Instead of having pickRoom call itself, you should use a loop of some kind!
The FS API bit also won't work – a file handle will never equal a string. You'll want h.readAll() == "true"
You could also improve by localizing more of your variables – be careful of scope issues!
shell.run("clear") is just plain bad practice, it's easily replaced by a call to term.clear and term.setCursorPos.

Dog, on 06 July 2017 - 06:04 AM said:

A couple of things I noticed:
1. You're indexing your table starting with 0, in Lua you'll want to start with 1 unless you specifically create a 0 based entry.
2. You're attempting to concatenate a string and number, which I don't *think* will work. You're probably getting the error you're getting because your number is nil.

EDIT: :ph34r:/> 'd

KingofGamesYami, on 06 July 2017 - 05:58 AM said:

Well, it's not the fs API. That won't throw that particular error. "concatenate" refers to the joining of two strings (the .. operator).
I'd say for whatever reason numbRoom is nil. Probably a misspelling, check lines 9 and 10. SquidDev is correct. (You also appear to have a misspelling later, calling "pickroom" not "pickRoom")
—–
I'd also like to point out that this function is endlessly-recursive which will lead to problems. Instead of having pickRoom call itself, you should use a loop of some kind!
The FS API bit also won't work – a file handle will never equal a string. You'll want h.readAll() == "true"
You could also improve by localizing more of your variables – be careful of scope issues!
shell.run("clear") is just plain bad practice, it's easily replaced by a call to term.clear and term.setCursorPos.

Dog, on 06 July 2017 - 06:04 AM said:

A couple of things I noticed:
1. You're indexing your table starting with 0, in Lua you'll want to start with 1 unless you specifically create a 0 based entry.
2. You're attempting to concatenate a string and number, which I don't *think* will work. You're probably getting the error you're getting because your number is nil. I believe you'll need to tostring() your number before concatenating.

EDIT: :ph34r:/> 'd

term.clear()
term.setCursorPos(1,1)
print("Lazuli Azure Resort and Spa")
print("---------------------------")
print(" ")
while true do
  room = {101, 102, 103, 201, 202}
  a = math.random(1,5)
  numbRoom = tostring(room[a])
  dir = "rooms/"..numbRoom
  h = fs.open(dir, "r")
  if h == "true" then
	term.clear()
	term.setCursorPos(1,1)
	print("Your room number is "..numbRoom..".")
	local g = read()
	h = fs.open(dir, "w")
	h.write("false")
	h.close()
	break
  end
end
os.shutdown()