Why doesn't this work

Questions
1

I’m trying to make my programs more effiecent by using more tables and functions.

function setup()
    fin = 1
end
function count(x)
    x = x + 1
    print(x)
end
function draw()
count(fin)
end

I want to make a function that counts up. (So it would go 1,2,3,etc) but it will just print fin+1 and keep that value

2

it doesn’t work because the x that the count function receives is just a copy of fin, not fin itself.

The easiest way to correct this is

--(1) no need to pass fin to the function
function count()  
   fin=fin+1
end

--or, 
--(2) if you want to use count with other variables as well
function count(x)
    x=x+1
    print(x)
    return x  --pass the value back
end

--and then in draw, you use count like this
fin=count(fin)
3

Ooh, so i was just making two pointers to the same value. Thanks @ignatz

4

@Progrmr235 - yes, you can think of numbers and strings as not having pointers at all, so they are always copied, whereas anything else (vec, table, image, …) is passed by pointer

5

Actually what I don’t understand is how is this

function setup()
x = 0
end
function count(x)
x = x + 1
print(x)
return x
end
function draw()
x = count(x)
end

more efficient then this

function setup()
x = 0
end
function draw()
x = x + 1
print(x)
end

the second one is easier to write and does the same thing.

6

who says one is more efficient than the other (not me) ?

7

Never said you said that @ignatz. I just assumed there’s an advantage to using functions you define because it’s more to write. I just can’t see what the advantage is.

8

No, the advantage of functions is that they

  • avoid duplicating code that gets used more than once,
  • makes your code easier to debug and test (because each function can be tested separately) and
  • make your code neater, eg
--this code....
function draw()
   --100 lines of code doing all sorts of things
end

--is much easier to read like this, with the code split into functions
function draw()
    SetupScreen()
    MovePlayer()
    MoveNPCs()
    ShowStats()
end
9

@Progrmr235 - with respect to the last example you posted, the first case definitely won’t be more efficient as you’ve got the memory overhead of the extra function and the setup / teardown time of the function call as well (granted it’s minuscule but all these little parts can build up over time) .

In this case, the function is there more to demonstrate the concept.
In practice you’d more likely take the approach suggested by @Ignatz - especially with respect to not duplicating code and also for organising code into logical sections.

Hope this helps
:slight_smile: