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Class array ? (2 dimensional)

 
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eb
Guest
PostPosted: Sun Jun 11, 2006 9:10 am    Post subject: Class array ? (2 dimensional) Reply with quote


Hello,

This *should* be simple, but I'm not knowledgeable enough so as to get it by
myself.

Suppose I want a double array of a custom class (say MyTile, to tile a
square).

How would I declare it in MyTiledSquare.h ?

I did not succeed with "MyTile **myTiles ;"
The trick is : I want the tiling size (the number of tiles per row / lines)
to depend on a variable. Therefore, I don't want to fix the array size
there.


Then, how would I initialise it in MyTiledSquare.cpp ?
The array size is dependent on a variable which is in the MyTiledSquare
class.

In the end, I would like to access an element with MyTile[i][j]

Thanks for any clues.
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Alan Johnson
Guest
PostPosted: Sun Jun 11, 2006 9:10 am    Post subject: Re: Class array ? (2 dimensional) Reply with quote


eb wrote:
Quote:
Hello,

This *should* be simple, but I'm not knowledgeable enough so as to get it by
myself.

Suppose I want a double array of a custom class (say MyTile, to tile a
square).

How would I declare it in MyTiledSquare.h ?

I did not succeed with "MyTile **myTiles ;"
The trick is : I want the tiling size (the number of tiles per row / lines)
to depend on a variable. Therefore, I don't want to fix the array size
there.


Then, how would I initialise it in MyTiledSquare.cpp ?
The array size is dependent on a variable which is in the MyTiledSquare
class.

In the end, I would like to access an element with MyTile[i][j]

Thanks for any clues.

You'll save yourself a lot of headache if you use std::vector. Example:

unsigned rows = 25, cols = 80 ;
std::vector< std::vector<T> > v(rows, std::vector<T>(cols)) ;

--
Alan Johnson
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eb
Guest
PostPosted: Mon Jun 12, 2006 9:10 am    Post subject: Re: Class array ? (2 dimensional) Reply with quote


Alan Johnson wrote:


Quote:

Or, if you want to do it all together:

size_t rows = 25, cols = 80 ;
std::vector< std::vector<QCanvasLine> > lines(rows,
std::vector<QCanvasLine>(cols, QCanvasLine(canvas))) ;


Close ... What dod the trick was :

std::vector< std::vector<QCanvasLine> > HGatter (board_size,
std::vector<QCanvasLine>(board_size, QCanvasLine::QCanvasLine(canvas))) ;



Now I can compile.

Unfortunately, the code does not work yet
(I have then the initialisation of each HGatter line, but they would not
show Sad )

int i,j;

for (i=0; i<board_size; i++)
for (j=0; j<board_size; j++)
{
HGatter[i][j].setPoints(offsetX + square_size * i, offsetY,
offsetX + square_size * i, offsetY + board_pixel_size);
HGatter[i][j].show();
}



Thanks anyway.
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