anybase^tm calculator (for some reason)

basecalc.lua

local charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

function ToBase10(num, curbase) -- tonumber has a static charset, we might want to change it in the future so we roll our own
	local out = 0
	num = tostring(num)

	for i = 1, #num do -- this goes left to right
		local cur = string.sub(num, i, i)
		local val = string.find(charset, cur)
		if not val then error("Number '" .. cur .. "' in base " .. curbase .. " not supported by charset '" .. charset .. "'") return end
		out = out + (val - 1) * (curbase ^ (#num - i))
	end

	return out
end

function BaseCalc(num, curbase, targetbase)
	if not targetbase then
		targetbase = curbase
		curbase = 10
	end

	num = ToBase10(num, curbase)

	local out = ""

	local mynum = num
	while true do
		local cur = math.floor(mynum % targetbase)
		local val = string.sub(charset, cur + 1, cur + 1)
		if not val then error("Number '" .. cur .. "' in base " .. targetbase .. " not supported by charset '" .. charset .. "'") return end
		out = val .. out

		local nex = math.floor(mynum / targetbase)
		if nex == 0 then break end

		mynum = nex
	end

	return out
end

--[[ tests
print("0x" .. BaseCalc(10000, 2, 16) == "0x10")
print(BaseCalc("ABC", 16, 10) == "2748")
--]]