prinitng 2D array form pointer ????

This is a discussion on prinitng 2D array form pointer ???? within the C Programming forums, part of the General Programming Boards category; Ok so here's my problem... I know this code works for a pointer of a 2Darray inside the same function, ...

  1. #1
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    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??
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  2. #2
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    the | after the < sign in the for loop is just my cursor, ignore.

  3. #3
    Epy
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    Can you just copy the code instead of posting a screenshot, I can hardly read that crap since it's so dark.

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    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");
    	
    }

  5. #5
    Registered User slingerland3g's Avatar
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    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.

  6. #6
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    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.

  7. #7
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    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...

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