Convertbase

function convertbase(num, ib, ob)

    num = tostring(num)

    local digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

    if ib == ob then return num end
    if ib > 36 or ib < 2 or ob > 36 or ob < 2 then return nil end

    local dec = 0

    if ib ~= 10 then
        -- Convert to Decimal
        local len = string.len(tostring(num))
        for i = 1,len do
            local d = tonumber(string.sub(num, i, i))
            dec = dec + (d * (ib) ^ (len - i))
        end
    else
        dec = num
    end

    -- Convert from Decimal to Output Base
    local str = ""
    repeat
        local d = (dec % ob) + 1
        dec = math.floor(dec / ob)
        str = string.sub(digits, d, d) .. str
    until dec == 0

    return str
end