Help with typedef struct name *name

[Creedy]

So I have a header file and a library with functions and in the header it declares
typedef struct board *board;

Now I have to use the functions from the header:
board create_board(int rows, int cols);

void cell_on(board b, int r, int c);

int display_board(board b);

void delay(int msec);



So in my program I:

#include "board.h"

int main(void){
  board b;

  create_board(24, 80);

  cell_on(b, 2, 2);

  display_board(b);

  delay(2000);

return 0;

}

And I am getting a segmentation fault. So I know something is wrong with me using b in the functions. Could anyone help? Thanks

[murugaperumal]

The problem may be, you may forget to allocate the memory for that *board.

If it is not a problem, then show us the coding for the following function

void cell_on(board b, int r, int c);

int display_board(board b);

void delay(int msec);

[grumpy]

b is an unitialised pointer. At a guess, the line

create_board(24, 80);

needs to be changed to;

b = create_board(24, 80);

If it's not that, then you need to look in the implementation of the various functions.

[Elysia]

Avoid typedefs of pointers. They confuscate things unneedlessly.
Furthermore, a board isn't a pointer to a board, so it's also misleading.
When I create a board, I take for granted that it will create a board. But a pointer to a board isn't a board, and therefore when I create a board in your code, I haven't created a board because it's uninitialized. Beware.

[Creedy]

Well the code for the functions was not given to me because it is an assignment.
But grumpy you were right... all I had to do was "b=", it makes sense now.
Thank you.

b is an unitialised pointer. At a guess, the line

create_board(24, 80);

needs to be changed to;

b = create_board(24, 80);

If it's not that, then you need to look in the implementation of the various functions.

[grumpy]

But grumpy you were right... all I had to do was "b=", it makes sense now.

Take note of Elysia's comments too. It is better to avoid unnecessary obfuscation when you can. People who have trouble understanding their own code also tend to have trouble getting it working correctly.

[Creedy]

Okay I will... It was my teacher's doing this time, he gave us that.

[Elysia]

If you're feeling up to it, you can also remark that to your teacher that we said so.
It's always fun to see how they react, and sometimes we might even make a teacher better.