Problems with Array

change initailize_board(char ** board) to initailize_board(char board[3][3])

btw, u misspelled initialize :-P. you also have to remember that an array is not a pointer (for example: an array cannot be an l-value but a pointer can).

Quote:

Original post by Hammonjj I'm trying to initialize and array of char to ' ', but I'm having some issues.

why not just do this?

::memset(gameBoard, 32, (sizeof(char) * 3 * 3)); // '32' is ASCII for " "

Hi , try
char gameBoard[3][3] = {' '};

/Kuppikeitto

Use char[3][]
or else malloc and pass the double pointer.

//Removed spammish signature

[Edited by - jbadams on October 27, 2007 6:01:34 AM]

Quote:

Original post by Kuppikeitto Hi , try char gameBoard[3][3] = {' '}; /Kuppikeitto

Nope, that sets the first element to ' ', the rest to 0.

Quote:

Original post by Verg Quote: Original post by Hammonjj I'm trying to initialize and array of char to ' ', but I'm having some issues. why not just do this? ::memset(gameBoard, 32, (sizeof(char) * 3 * 3)); // '32' is ASCII for " "

Dont use 32, just use ' ', it will compile the same and is far more readable:
::memset(gameBoard, ' ', (sizeof(char) * 3 * 3));

Don't write sizeof(char) (except implicitly via a template that has a sizeof(T)); sizeof(char) == 1 everywhere, always, by definition. Also, in C++, use std::fill instead.

But the main conceptual problem for the OP is that a char[3][3] is actually one-dimensional storage: 9 chars of memory in a row are reserved, and there is nothing put into memory at any time during program execution that indicates the division into 3 "rows" of 3 chars each. All of that interpretation is done at compile time.

If you want a real multi-dimensional array, then use - well, it depends on your requirements. If you really do know the size ahead of time (e.g. for a tic-tac-toe board), then a boost::array of boost::arrays is appropriate:

typedef boost::array<boost::array<char, 3> 3> board_t;board_t board;// If you only need to initialize boards of that size:void initialize_board(board_t& b) {  // access b[j] just as you'd expect to be able to}// If, for any given board, you'll know its size in advance BUT you need to// initialize multiple sizes of boards, you can use templates:template<int x, int y>void initialize_board(boost::array<boost::array<char, x>, y>& b) {  for (int j = 0; j < y; ++j) {    for (int i = 0; i < x; ++i) {      // some complicated calculation goes here    }  }}

You can also use std::fill on each row of a boost::array. (I don't think it will necessarily work over the whole thing because of structure padding.)

If you need the array to be rectangular, but you don't know its size ahead of time, then boost::multi_array is appropriate:

typedef boost::multi_array<char, 2> board;// this time, the int parameter to the template is the dimensionality.void initialize_board(board& b) {  for (int j = 0; j < b.shape()[1]; ++j) {    for (int i = 0; i < b.shape()[0]; ++i) {      // some complicated calculation goes here    }  }}

And you can std::fill the multi_array all in one go to initialize each element to the same value (it provides a .begin() and .end(), so you don't even have to fiddle with array indices to make that work).