• Orgoton <orgoton mindless.com> Feb 25 2007
• Bill Baxter <dnewsgroup billbaxter.com> Feb 25 2007
• Orgoton <orgoton mindless.com> Feb 25 2007
• Frits van Bommel <fvbommel REMwOVExCAPSs.nl> Feb 25 2007

Orgoton <orgoton mindless.com> writes:

Another Roadside Attraction Wrote:

 I'm learning D by writing a logic game with a grid-shaped board. If possible,
I'd like to use a rectangular array for the board, but I'd like to define the
width of the board at runtime when I instantiate the class. Ideally, I'd like
to do something like this:
 
 public class Board {
 	
 	private Piece[,] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width,width];
 	}
 
 }
 
 But that doesn't compile. It looks like the dimensions of rectangular arrays
has to be known at compile-time. Is that right, or am I missing something?
 
 I've also tried declaring the array as an ordinary multi-dimensional array,
but this doesn't compile either:
 
 public class Board {
 	
 	private Piece[][] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width][width];
 	}
 
 }
 
 What's the best way to write this code? As I expand on this project, I plan on
incorporating some time-consuming algorithms (think, n-Queens problem), so I'd
prefer to use the most efficent data structure possible for the board.
 
 Thanks!!
 
 --ARA



You can declare a variable length array by doing something like

int numbers[];

//in runtime on the program:::
numbers.length=size;
//for bidimensionality:
int table[][]; //or matrix
table.length=HowManyCollumns;
foreache (int[] row, table[]) row.length=HowManyRows; //or the size of the
collumn

See also:
http://www.digitalmars.com/d/arrays.html

Specially the dynamic array thingy. This is the best solution I have for you
and I belive this one to be the simplest you got so far.

Bill Baxter <dnewsgroup billbaxter.com> writes:

Orgoton wrote:
 Another Roadside Attraction Wrote:
 
 I'm learning D by writing a logic game with a grid-shaped board. If possible,
I'd like to use a rectangular array for the board, but I'd like to define the
width of the board at runtime when I instantiate the class. Ideally, I'd like
to do something like this:

 public class Board {
 	
 	private Piece[,] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width,width];
 	}

 }

 But that doesn't compile. It looks like the dimensions of rectangular arrays
has to be known at compile-time. Is that right, or am I missing something?

 I've also tried declaring the array as an ordinary multi-dimensional array,
but this doesn't compile either:

 public class Board {
 	
 	private Piece[][] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width][width];
 	}

 }

 What's the best way to write this code? As I expand on this project, I plan on
incorporating some time-consuming algorithms (think, n-Queens problem), so I'd
prefer to use the most efficent data structure possible for the board.

 Thanks!!

 --ARA


 
 You can declare a variable length array by doing something like
 
 int numbers[];
 
 //in runtime on the program:::
 numbers.length=size;
 //for bidimensionality:
 int table[][]; //or matrix
 table.length=HowManyCollumns;
 foreache (int[] row, table[]) row.length=HowManyRows; //or the size of the
collumn
 
 See also:
 http://www.digitalmars.com/d/arrays.html
 
 Specially the dynamic array thingy. This is the best solution I have for you
and I belive this one to be the simplest you got so far.


How is that simpler than
     auto table = new int[][](HowManyRows,HowManyColumns);
??

Orgoton <orgoton mindless.com> writes:

Bill Baxter Wrote:

 Orgoton wrote:
 Another Roadside Attraction Wrote:
 
 I'm learning D by writing a logic game with a grid-shaped board. If possible,
I'd like to use a rectangular array for the board, but I'd like to define the
width of the board at runtime when I instantiate the class. Ideally, I'd like
to do something like this:

 public class Board {
 	
 	private Piece[,] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width,width];
 	}

 }

 But that doesn't compile. It looks like the dimensions of rectangular arrays
has to be known at compile-time. Is that right, or am I missing something?

 I've also tried declaring the array as an ordinary multi-dimensional array,
but this doesn't compile either:

 public class Board {
 	
 	private Piece[][] grid;
 	
 	public this(uint width) {
 		grid = new Piece[width][width];
 	}

 }

 What's the best way to write this code? As I expand on this project, I plan on
incorporating some time-consuming algorithms (think, n-Queens problem), so I'd
prefer to use the most efficent data structure possible for the board.

 Thanks!!

 --ARA


 
 You can declare a variable length array by doing something like
 
 int numbers[];
 
 //in runtime on the program:::
 numbers.length=size;
 //for bidimensionality:
 int table[][]; //or matrix
 table.length=HowManyCollumns;
 foreache (int[] row, table[]) row.length=HowManyRows; //or the size of the
collumn
 
 See also:
 http://www.digitalmars.com/d/arrays.html
 
 Specially the dynamic array thingy. This is the best solution I have for you
and I belive this one to be the simplest you got so far.


 How is that simpler than
      auto table = new int[][](HowManyRows,HowManyColumns);
 ??


To my opinion. Yours may differ. Creating buffers using .length is much more
immediate than using new. Also, resizing the same buffers is much simpler. Sure
the "foreach" stuff is cumbersome, but the OP mentioned he is learning D, so
it'd be best if he gets the properties of (dynamic) arrays and the foreach
(which is nothing more than a simplification of common for loops).

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Orgoton wrote:
 Bill Baxter Wrote:
 
 Orgoton wrote:
 You can declare a variable length array by doing something like

 int numbers[];

 //in runtime on the program:::
 numbers.length=size;
 //for bidimensionality:
 int table[][]; //or matrix
 table.length=HowManyCollumns;
 foreache (int[] row, table[]) row.length=HowManyRows; //or the size of the
collumn

 See also:
 http://www.digitalmars.com/d/arrays.html

 Specially the dynamic array thingy. This is the best solution I have for you
and I belive this one to be the simplest you got so far.


      auto table = new int[][](HowManyRows,HowManyColumns);
 ??


 To my opinion. Yours may differ. Creating buffers using .length is much more
immediate than using new. Also, resizing the same buffers is much simpler. Sure
the "foreach" stuff is cumbersome, but the OP mentioned he is learning D, so
it'd be best if he gets the properties of (dynamic) arrays and the foreach
(which is nothing more than a simplification of common for loops).


IIRC it's also pretty much exactly what 'new' will do internally (except 
it does it more generically). Do you always consider re-implementing the 
standard library "simpler"?