2D Array as Parameter w/ Unknown Size

[Daker3]

Is it possible to pass 2D arrays as a parameter without knowing the size? The effect I'm trying to get is:

void print(double a[][], int row, int col){//Print 2D array}

That way I can just make a method that works with different sizes. I was thinking of using pointers to get around needing to set a size, but I'm not sure how to go about it. So, is there a way to do this:

void print(double **a, int row, int col){//Print 2D array}

I'm trying to make a matrix class.

[Zhuge]

Those two functions are in fact, identical. Arrays passed to functions are automatically converted to pointers. The method you are showing would be a standard way to handle an array passed as a parameter...though wouldn't you want this function to be a method of your matrix class, and have it print the internal array?

[Daker3]

Yeah, I had it implemented as a class method, but I just wanted to see if I can rewrite print just to test out pointers. I still can't seem to get it to work. If I use the second function, it doesn't work with my 2D array.

double A[2][2] = {{1, 2}, {2, 3}}
print(A, 2, 2);

It gives me an error. "cannot convert parameter 1 from 'double [2][2]' to 'double **"

[Texan40]

pass in (&A,2,2) instead

[Daker3]

If I use (&A, 2, 2) I get: "cannot convert parameter 1 from 'double (*)[2][2]' to 'double **'"

[Peter87]

You can't convert the 2D array to a double**. It's a common misconception.

To pass the 2D array you have to at least specify the second size.
void print(double a[][2], int rows){}

Another way is to use templates

template <int ROWS, int COLS>
void print(double (&a)[ROWS][COLS]){} 

[Texan40]

Ah, you are right. Would the row/col indexing be horrible cumbersome if you just passed a plain ol' pointer to double?

[danoc93]

Using functions it would be better to define the maximum possible value your array could acquire... then pass the array