Multidimensional array returns nil.

[KayleMaster]

Code: Select all

terrain_chunk = {}          
            for i=chunk_width,1,-1 do
              terrain_chunk[i] = {}     
              for j=chunk_height,1,-1 do
                terrain_chunk[i][j] = 1
              end
            end

Code is located in love.load
I followed a tutorial on the love website which I can't seem to find anymore for some reason
It was called matrices and multidimensional arrays. I come from game maker and arrays there are handled better.
I have no idea how to do this, any ideas?

[raidho36]

What do you mean "returns nil"? Throws an error of nil reference? The code itself works fine. You can get a nil if you reference a key that doesn't exist in the table, but then if the "first bracket" reference resolved to nil, trying to resolve the second one will crash the game, it's the same as trying to do "nil[j]" and obviously it won't work.

You should allocate arrays in normal order, not reverse. GameMaker suffers performance-wise when you do it in normal order because it reallocates the array constantly, and in reverse it does it once. In LUA reallocation goes progressively less often as array grows so it's not of any concern. Plus, because of the way it works, you'll actually get better performance if you allocate it in normal order, one by one.

Just so you know, tables in LUA are hash-tables. It means they can have both integer keys and string keys. For what it's worth, any variable can pass for a key in LUA, even other tables. You can access literal keys with dot notation.

Code: Select all

foo[1] = "bar"
foo["bar"] = 10 
foo.bar = 100 --last two are equivalent

[zorg]

Just so you know, tables in LUA are hash-tables. It means they can have both integer keys and string keys. For what it's worth, any variable can pass for a key in LUA, even other tables. You can access literal keys with dot notation.

Just tiny nitpicking:

The one value you cannot have as a table index is nil.

Literals, according to at least wikipedia, include numbers and booleans (in lua), not just strings, and in lua, you can't use the dot notation on neither numbers, nor boolean true and false.
You probably meant to say string keys instead.

Finally, i personally don't care about this one, but it's really called lua, not LUA.
LUA => L.U.A. => Lua est pas Un Acronyme. Lua is not an acronym.

[raidho36]

Well, to be perfectly nitpicky, nil is not a variable.

By "literal" I meant of course the ones that are valid stings for variable names.

Also, pretty sure it's all capitals. It means "moon" in portugese or some shit. Or I think it used to be all caps at some point? Now it says the proper spelling is "Lua".

[zorg]

Apparently, Roberto always disliked LUA since it's not an acronym, as i've said; it's a simple word, as you said, meaning moon in portuguese, so it's just plain "lua".

Also, a number, a bool, a string literal ain't a variable either; you did say "For what it's worth, any variable can pass for a key in LUA, even other tables."; I meant that your variable can be anything, but nil, even though you can set a variable to it.

[Positive07]

Nitpicking game! I'm in!

It's a name so Lua (no LUA because that is an acronym, not lua because it's used as a proper name so it should be capitalized)

And I'm with zorg here, tables can use number, strings, tables, userdata, functions and booleans as indexes, nil is not a valid index.

[KayleMaster]

Oops, forgot about the topic!
I actually fixed it, I don't know how, but here's the current code:

Code: Select all

	        
	   terrain_chunk = {}          

            for y = 0,cols do
                local row = {}
                    for x = 0,rows do
                        row[x]=love.math.random(8);
                    end
                terrain_chunk[y]=row;
            end

[pgimeno]

Whatever the problem was, it's clear it wasn't in the snippet you copied, because that one worked just fine.

[KayleMaster]

Yeah, It was somewhere else in the code.