Thread: prinitng 2D array form pointer ????

Ok so here's my problem... I know this code works for a pointer of a 2Darray inside the same function, but when I try to do the same for a 2D array pointer passed by reference it obviously won't work... any help??

the | after the < sign in the for loop is just my cursor, ignore.

Can you just copy the code instead of posting a screenshot, I can hardly read that crap since it's so dark.

Code:

/************************************************************************************
 print_matrix():
 This will print the contents of the matrix M which has r rows and c  
 columns.  The matrix will be printed one row per line.  Each row will  
 be printed between pipe characters('|').  Each element of the vector  
 will have a field width of 8 and each element will be left aligned  
 within that field. 
 ************************************************************************************/
void print_matrix(int *M, int r, int c)
{
	
	int (*p)[c], i;
	
	for ( p = M; p < &M[r]; p++ )
	{
		printf("\n|");
		for ( i = 0; i < c; ++i)
		{
			printf("%d", (*p)[i]);
			if ( i == (c-1)) printf("|");
		}
	}		
	
	printf("\n");
	
}

You will have to pass in the 2d array and give its dementions. Your declaration is off.

Code:

void print_matrix(int **M, int width, int length)

There are a few other ways to accomplish this.

Your array traversal logic would be correct if M were an int **. However, since M is an int *, your row "pointer" must increment by c elements each time, assuming row major ordering.

thanks. I solved it with this:

Code:

void print_matrix(int *M, int r, int c)
{
	
	int i, j, k=0;
	
	for ( i = 0; i < r; ++i )
	{
		printf("\n|");
		for ( j = 0; j < c; ++j)
		{
			printf("%d\t", M[k++]);
			if ( j == (c-1)) printf("|");
		}
	}		
	
	printf("\n");
	
}

the output is ........ty, but that's what my professor wants.. i guess i could improve it without it hurting my grade but i ahve to turn it in in an hour and i have one more method to work on...