Thread: Passing 2D arrays between functions

Pass it with pointers.

void blackNWhite(float array[height][width])
Rise and repeat. Know that you must specify the outer dimension for it to compile.

Originally Posted by Elysia

void blackNWhite(float array[height][width])
Rise and repeat. Know that you must specify the outer dimension for it to compile.

Yuck.

Code:

void blackNWhite(float * array, const size_t rows, const size_t columns)

Yum.

I tried this basic one:

Code:

void func(char array[])
{
	char name[255];
	strncpy(name, array, 255);
	printf("%s\n", name);
	int twoD[5][5];
	int i, j;
	for(i=0; i<5; i++)
	{
		for(j=0; j<5; j++)
		{
			twoD[i][j] = i;
		}
	}
	func2(twoD);
}

void func2(int array[][5])
{
	int i, j;
	for(i=0; i<5; i++)
	{
		for(j=0; j<5; j++)
		{
			printf("%d\n", array[i][j]);
		}
	}
}

But i get the error:

Code:

func.h:28: warning: conflicting types for ‘func2’
func.h:25: warning: previous implicit declaration of ‘func2’ was here

Actually works now, but how could I do it by passing via pointers?

Originally Posted by zacs7

Code:

void blackNWhite(float * array, const size_t rows, const size_t columns)

Yuck. 2D arrays as 1D array.

Code:

void blackNWhite(float array[height][width])

2D array as 2D array. Yum.

As for the question, cast the array to float* when you pass it. Pass along the rows and columns to the function, too.
And as for the warning, you forgot to make a prototype for the function.

what about this:

Code:

....
int twoD[height][width];
//DO SOMETHING
func2(twoD, height, width);
....

void func2(int array[][], height, width)
{
	int i, j;
	for(i=0; i<height; i++)
	{
		for(j=0; j<width; j++)
		{
			printf("%d\n", array[i][j]);
		}
	}
}

How can i pass that array? Whats the best way to do that?

When you pass a 2D-array, you must specify the size of the outer-most dimensions. I showed with an example before. You had to fill in the width in the array. The height would be optional, but the width is required.
Or pass an int* along with height & size. It will be treated as a 1D array, however.