Question

Even though Lua does not differentiate between floating point numbers and integers, there are some cases when you want to use integers. What is the best way to covert a number to an integer if you cannot do a C-like cast or without something like Python’s int?

For example when calculating an index for an array in

idx = position / width

how can you ensure idx is a valid array index? I have come up with a solution that uses string.find, but maybe there is a method that uses arithmetic that would obviously be much faster. My solution:

function toint(n)
    local s = tostring(n)
    local i, j = s:find('%.')
    if i then
        return tonumber(s:sub(1, i-1))
    else
        return n
    end
end

Answer 1

You could use math.floor(x)

From the Lua Reference Manual:

Returns the largest integer smaller than or equal to x.