CODEWITHSUNDEEP
carrays
Jack Morton
Jack Morton

Reputation: 199

2d array rows/columns length C

I need to declare a 2d array to represent the size of chess-board. However, I'm having a trouble understanding how would I actually calculate the width and the length of the board. I would like to know how could I calculate size of the rows and columns of my 2d array

Say, int boardSize[5][5]? 

int main()
{
   int boardSize[5][5];
   int boardWidth=?
   int boardHeight =?
   createBoard(boardWidth, boardHeight);
}

 int createBoard(int width, int height)
 {
   // code that actually creates board //
 }

Sorry, for not being specific in the begging. So, here I need to calculate boardwidth and boardheight variables? How do I do that from the declared array above. Thank you!

Upvotes: 6

Views: 21133

Answers (4)

Lundin
Lundin

Reputation: 213711

This is easily fixed with the removal of all mysterious magic numbers from your code.

#define BOARD_WIDTH  8
#define BOARD_HEIGHT 8


square_t board [BOARD_WIDTH][BOARD_HEIGHT];

createBoard (board, BOARD_WIDTH, BOARD_HEIGHT);


void createBoard (square_t* board, int boardWidth, int boardHeight)
{

}

Upvotes: 0

Aftnix
Aftnix

Reputation: 4589

printf("Size of the board in bytes %d\n", sizeof(boardSize));
printf("Size of column size in bytes %d\n", 5*sizeof(int));
printf("Size of row in bytes %d\n", 5*sizeof(int));

If you want leave the board as statically allocated the declare it as global like,

static int board[5][5];

Then traverse it in your "createBoard" method(I hate Hungarian notations) for correct initialization :

for(i = 0; i < hight; i++)
  for(j = 0;j< width; j++)
     board[i][j] = <initialization stuff>

or you can dynamically allocate it in your createBoard() method. In that case do not declare as local variable for main.

int * createBoard(int hight, int width){
   int * board;
   if(board = malloc(sizeof(int) * hight * width))
       return board;
   return NULL;
}

in main() you can do something like this:

 int * board = createBoard(5,5);
 if(!board)
     printf("Allocation failure \n");
     exit(EXIT_FAILURE);

Upvotes: 0

Jens Gustedt
Jens Gustedt

Reputation: 78903

boardSize[0] gives you the first row of the matrix, boardSize[0][0] the first of its elements. So the quantities you are looking for are sizeof boardSize/ sizeof boardSize[0] and sizeof boardSize[0]/ sizeof boardSize[0][0].

BTW: use size_t as a type for sizes, not int.

Upvotes: 8

unwind
unwind

Reputation: 399803

If you say

int boardSize[5][5];

that gives you a 2D array of integers, 5 by 5 in size. So it will have 5 rows of 5 columns each, for a total of 25 integers.

Upvotes: 0

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