How to iterate through table in Lua?

Question

So, I have a table something along these lines:

arr = {   apples = { 'a', "red", 5 },   oranges = { 'o', "orange", 12 },   pears = { 'p', "green", 7 } } 

It doesn't seem like it's possible to access them based on their index, and the values themselves are tables, so I just made the first value of the nested table the index of it, so it now looks like this:

arr = {   apples = { 0, 'a', "red", 5 },   oranges = { 1, 'o', "orange", 12 },   pears = { 2, 'p', "green", 7 } } 

So, now any time I use one of these tables, I know what the index is, but still can't get to the table using the index, so I started to write a function that loops through them all, and check the indexes until it finds the right one. Then I realized... how can I loop through them if I can't already refer to them by their index? So, now I'm stuck. I really want to be able to type arr.apples vs arr[1] most of the time, but of course it's necessary to do both at times.

Answer 1

To iterate over all the key-value pairs in a table you can use pairs:

for k, v in pairs(arr) do   print(k, v[1], v[2], v[3]) end 

outputs:

pears   2   p   green apples  0   a   red oranges 1   o   orange 

Edit: Note that Lua doesn't guarantee any iteration order for the associative part of the table. If you want to access the items in a specific order, retrieve the keys from arr and sort it. Then access arr through the sorted keys:

local ordered_keys = {}  for k in pairs(arr) do     table.insert(ordered_keys, k) end  table.sort(ordered_keys) for i = 1, #ordered_keys do     local k, v = ordered_keys[i], arr[ ordered_keys[i] ]     print(k, v[1], v[2], v[3]) end 

outputs:

  apples  a   red     5   oranges o   orange  12   pears   p   green   7