--[[

Tables in Lua may contain both ordered (numbered) and unordered
(named) members. Most of the time, you'll use just named
elements, or just numbered elements, but there are surprisingly
frequent occasions when it's useful to use both. You then need
to remember if you iterate through members that ...

* #tablename will only go through numbered elements, and will
give you nil if there's a gap in the numbering

* pairs will take you through all elements with non-nil values,
but won't give you any members which are explicitly or implicitly
set to nil

* ipairs will start at the element numbered 1, and go up through
numbered elements until it reaches a nil, at which point it will
go no further.

]]

print ("Set up a table, indexed, with a hole")
print ("Iterate through it using #tablename")
vals = {"one","two","three",nil,"five"}
for k=1,#vals do
        print (k,vals[k])
        end
print ("------------- ")

print ("Add a numbered value after a gap. Works fine")
vals[8] = "eight"
for k=1,#vals do
        print (k,vals[k])
        end
print ("------------- ")

print ("Add a named value - but not seen by the loop")
vals["nine"] = "It's 9"
for k=1,#vals do
        print (k,vals[k])
        end
print ("------------- ")

print ("Pairs goes through all the elements with values")
for k,v in pairs(vals) do
        print (k,v)
        end
print ("------------- ")

print ("Ipairs starts at element 1, goes up 1 at a time and stops when it finds a nil")
for k,v in ipairs(vals) do
        print (k,v)
        end
print ("------------- ")