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hymerman

I am a stupid moron and cannot program

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Bloody hell, I'm having an off day today. I can't believe I can learn and implement a wxWidgets GUI, a setting manager, dators and a templated generalised singleton in a week but can't figure out how to create an array... Hopefully someone can help me out here :) Now, why won't this code work?:

struct tile {
  int type;
};

class whatever {
public:
  whatever();
  tile* environment;
}

whatever::whatever() {
  environment = new tile[100][100];
}

Obviously I've simplified my code somewhat, but these are the relavant bits... So, how about it then? How do I declare a 2D array of tiles, and define it later?

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You can't new a 2D array. Use a 1D array and throw in some inline function to translate an (x,y) into an absolute 1D index.

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You can't use new in that manner. I suggest creating a 1D array of size x*y. Then to access a particular tile use the following:
array[tileY*sizeX+tileX];

Or if you really want 2D arrays:


tile** array;
...
array = new tile*[x];
for(int i=0; i<x; ++i)
array = new tile[y];
...
tile t = array[x][y];





hope that helped.

[Edited by - Sam Gamgee on January 10, 2006 2:22:11 PM]

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Alternative:

boost::multi_array

~~~begin quote from teh docs~~~

Short Example


What follows is a brief example of the use of multi_array:

#include "boost/multi_array.hpp"
#include <cassert>

int
main () {
// Create a 3D array that is 3 x 4 x 2
typedef boost::multi_array<double, 3> array_type;
typedef array_type::index index;
array_type A(boost::extents[3][4][2]);

// Assign values to the elements
int values = 0;
for(index i = 0; i != 3; ++i)
for(index j = 0; j != 4; ++j)
for(index k = 0; k != 2; ++k)
A[j][k] = values++;

// Verify values
int verify = 0;
for(index i = 0; i != 3; ++i)
for(index j = 0; j != 4; ++j)
for(index k = 0; k != 2; ++k)
assert(A[j][k] == verify++);

return 0;
}



~~~end quote from teh docs~~~

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