turtle.getItemCount and turtle.select loop

Im new to the forum and programming so i need help pls
I need a loop that detects if there is an item in slot 1-16 if not go to the next slot and i dont know how to do that.
the program i made creates a part for a mobspawner








for trap=1,4 do

for ry=1,3 do

for w=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnRight()
turtle.forward()
turtle.turnRight()

for yc=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnLeft()
turtle.forward()
turtle.turnLeft()

end

for qs=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnRight()
turtle.forward()
turtle.turnRight()

for ts=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnLeft()
turtle.forward()
turtle.turnLeft()

for tz=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnRight()
turtle.forward()
turtle.down()
turtle.turnRight()

for ty=1,9 do
turtle.placeDown()
turtle.forward()
end

turtle.back()
turtle.turnLeft()
turtle.forward()
turtle.turnLeft()

for qy=1,9 do
turtle.Down()
turtle.forward()
end

turtle.back()
turtle.turnRight()
turtle.up()
turtle.forward()

end

What you ask for is a common design problem I run into a lot. Try this:

function selectItem()
    for s = 1, 16 do
        if turtle.getItemCount(s) > 1 then
            turtle.select(s)
            return true
        end
    end
    return false
end

This is a little, self-contained function that will simply select a slot with inventory. I put > 1 to preserve the catalog in the inventory (useful if you have more than one kind of item in the inventory). If your inventory is all the same, change that to > 0.

To use:

selectItem()
turtle.placeDown()

You could wrap the two lines into another function to make it easier to maintain and self-document:

function placeItem()
    if selectItem() then
        turtle.placeDown()
    else
        error("Ran out of inventory!")
    end
end

And to use:

placeItem()

Hope that helps.

Thank you very much works perfect now i didtn thought of a function i tried it with while loops i note this for the next time ill need