Lua and 3 requirement "if" statements

Question

I'm fiddling with some code I found on some forums, but I've only ever learned Java, so I'm a little out of my element. Here's the snippet I'm playing with:

/run 
function FnH() 
  for i=0,4 do 
    for j=1,GetContainerNumSlots(i) do 
      local t={GetItemInfo(GetContainerItemLink(i,j) or 0)}
      if t[7]=="Herb" and select(2,GetContainerItemInfo(i,j))>=5 then 
        return i.." "..j, t[1]
      end 
    end 
  end
end

This is using WoW's addon API. With what little I know, this is a search and make a list function that lists items that let t[7]=Herb while also having more than 5 of them. If Lua does arrays similarly, t[0] should be Item Name. I want to exclude an item with the name "blahblah", but I don't understand Lua's boolean operands.

In Java, it would be something along the lines of

if(itemX.getItemType()=="Herb" && itemX.getAmount()>5 && itemX.getName()!="blahblah")
do stuff
else skip to next item

I see with Lua that they use "and" and "or", but how do I say "and not this"?

Answer 1

If Lua does arrays similarly, t[0] should be Item Name.

Note that Lua indexes tables starting from index 1, not 0 like some other languages, so if you have table local t = {"John", "Laura", "Herb"}, then t[1] == "John" and t[3] == "Herb".

As others have said, the equivalent Lua operations are and, or, and not, with inequality written as ~=, so the code you have can be written as:

if itemX.getItemType() == "Herb"
and itemX.getAmount() > 5
and itemX.getName() ~= "blahblah" then
  -- do stuff
else
  -- skip to next item
end

You can also change the last condition to and not (itemX.getName()=="blahblah") as these are equivalent.

Also, I'm not sure about WoW API, but those itemX calls should probably be itemX:getItemType(), itemX:getAmount() and so on (note using : notation instead of . notation); see OO-programming section in Programming in Lua.

Answer 2

I'm just going to translate your java code straight to Lua, and you can see if it makes sense to you

    if itemX.getItemType() == "Herb" and itemX.getItemAmount() > 5 and itemX.getItemName ~= "blahblah" then do
        --do stuff here
    end
    else
        --skip to the next item
    end