Variable and string concat to select variable in lua - variables

Question

I have a set of variables that holds quantity info and x to select the one I use. How can I concatenate the letter s and var x and have it read as s2 or s3 etc. The code I managed to find does not work.
x = 2
s1 = false
s2 = 64
s3 = 64
s4 = 64
s5 = 0
if s2 >= 0 then
x = 2
elseif s3 >= 0 then
x = 3
elseif s4 >= 0 then
x = 4
elseif s5 >= 0 then
x = 5
end
if turtle.placeDown() then
tryUp()
turtle.select(1)
_G["s"..x] = _G["s"..x] - 1
end

Answer 1

Why would you need to do that?
My suggestion to improve your code would be something like this:
local s = {false, 64, 64, 64, 0}
for i = 2, #s do
if s[i] >= 0 then
x = s[i]
end
end
if turtle.placeDown() then
tryUp()
turtle.select(1)
x = x-1
end
Using a loop makes the code somewhat neater, and there is no real need for you to use global variables. If you insist on using _G with the string concatenation with your original code, try this:
x = 2
s1 = false
s2 = 64
s3 = 64
s4 = 64
s5 = 0
if s2 >= 0 then
x = "2" --Notice the string here
elseif s3 >= 0 then
x = "3"
elseif s4 >= 0 then
x = "4"
elseif s5 >= 0 then
x = "5"
end
if turtle.placeDown() then
tryUp()
turtle.select(1)
_G["s"..x] = _G["s"..x] - 1
end
This replaces all the x values with strings instead of numbers, which was probably what was causing the error