[Solved] Temporary variables

General Discussion Other

mentecode

in General Discussion • Other • 7 months ago

Hello all.

While fiddling with saving files ( Saving Game Level), an idea came.
I want to know if it is possible to create temporary array variables using for() loops during the running sketch, so I could save each level as a 2D array in-game, and recover them later. It would be a hassle to hard-code 100 array variables into the game, in case the user would like to play that many levels.
Is this possible?

Thanks,
-MenteCode.

Replies(11)

asimes

Re: Temporary variables

7 months ago

It is possible to save an array and retrieve it later, but not outside of its scope. You'd have to make it a global array for other functions to be able to use it.

If you mean saving in the sense that when someone turns off the sketch that the level would still be there then you'd have to save the level to a separate file.

PhiLho

Re: Temporary variables

7 months ago

" It would be a hassle to hard-code 100 array variables into the game"
You can make arrays of arrays... (that's what 2D arrays are, anyway).

And the general answer to your question is: yes.

mentecode

Re: Re: Temporary variables

7 months ago

Hello PhiLho,

In case you're thinking that the level is stored on a regular array (int[]), I'll tell you this:
Each and every level is stored on a 2D array, and I was told that nested, and 3D arrays aren't possible, and I should try to use an array of objects. I want to have each level on a variable, so if the player would like to go back, the level is ready to go. Is it possible to make an array of 2D arrays, and how would you do that?

Thanks,
- MenteCode.

quarks

Re: Temporary variables

7 months ago

I was told that nested, and 3D arrays aren't possible

Not true - it is possible to make arrays of any depth (although they become tedious and slow to iterate over)

A 2D array is an array of arrays
A 3D array is an array of 2D arrays
A 4D array is an array of 3D arrays
...

So here is a 3D array of integers.

int [][][] a3d = new int[10][10][10]; // 1000 elements

mentecode

Re: Re: Temporary variables

7 months ago

Hi quarks.

I didn't know that. Thanks a lot!

Can I take advantage of using the 3D array to save each level individually?

And is there a way of saving each 2D array to a file?

That will have answered both of my questions on this forum.

Thanks,

- MenteCode.

quarks

Re: Temporary variables

7 months ago

Can I take advantage of using the 3D array to save each level individually?

And is there a way of saving each 2D array to a file?

I assume that the 2D array represents a level and the 3D array holds all the levels? In which case the answer is yes. Actually most things are possible it is just that some are harder than others.

So if I have made the right assumptions then the 'unit' of saving is a 2D array which represents a 'level' so what you have is

int[][][] gameData = new int[nbrLevels][w][h]
// where width w and height h is the size of the array for a single level
// now here we have the definition of a level
int[][] level = new int [w][h];
// to assign this to the game at level 3 (array index starts at 0)
gameData[2] = level;

and getting level 1 would be

level = gameData[0];

There are several techniques that could be used to save the data to disc.

mentecode

Re: Re: Temporary variables

7 months ago

How do I know that using array[] will change the first dimension in array [ ] [ ][ ]?

Thanks,

MenteCode.

quarks

Re: Temporary variables

7 months ago

How do I know that using array[] will change the first dimension in array [ ] [ ][ ]?

It is defined that way in the Java language specoifiction.

If we have

int[][][] gameData = new int[nbrLevels][w][h];

then

gameData[0][1][2] is an int
gameData[0][1] is an array of of integers
gameData[0] is an array of arrays of ints (2D array) and
gameData is an array of arrays of arrays of ints (3D array)

so

gameData.length; returns the number of 2D arrays (i.e. levels)

mentecode

Re: Re: Temporary variables

7 months ago

Oh.

Sorry. I don't think I asked that question properly.

What I meant to ask was if the 3D array was a cube, where would it start?

At the top, or at the bottom?

Thanks for your reply.

- MenteCode.

GoToLoop

Re: Temporary variables

7 months ago

Just to add up from quarks.

Java knows how many dimensions an Array has! You declared it so yourself!

To obtain a "target" stored value, like an int, you have to specify all of its dimensions as indices.
If you specify less, what you got instead is a memory address/reference of the next dimension,
not what you have stored there!

quarks

Re: Temporary variables

7 months ago

What I meant to ask was if the 3D array was a cube, where would it start?

At the top, or at the bottom?

You as the programmer have to decide how the array is interpreted. In many instances it would make no difference provided you keep to the same scheme thorught your program.

In the game data example then there is a difference, because the 3D array is an array of game levels where each level is a 2D array. In that case the first index should be the level so that the identifier gameData[0] represents a level making it easier to manipulate the level data.

Top Reply