Passing 2D arrays between functions

Im a bit confused how I would do the following:
I have the following functions:

Code:

void bkSub(char arrayIn[])
void blackNWhite()
void cC()

Now this is what the flow I am looking for:

bkSub()
This function after receiving the arrayIn and processing it should pass a new 2D array (float array[height][width]) it created down to blackNWhite()
blackNWhite()
This function now receives that 2D array (float array[height][width]), processes it and passes it down to cC()
cC()
This now receive the 2D array as above and processes it and then passes back to main a structure info.

I am not sure how to do the passing of the 2D array between the functions.
Could someone help?

Pass it with pointers.

Yea I know that but not sure how with 2D arrays

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.

Implicit declaration == "I forgot to write a prototype for that function."

If you want to write a function that can handle arbitrarily-sized arrays, you would need to pass in the memory address of the array itself, and its sizes.

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?

If you want your func2 to be able to handle any-sized array, the first parameter need to be an int *, and inside you need to handle the arithmetic yourself.

We just did this fairly thoroughly Friday last week, I think; so, as heretical as it may seem, you may need to read someone else's posts to find more information.

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.