Re: print matrix

From: Arthur J. O'Dwyer (ajo_at_nospam.andrew.cmu.edu)
Date: 06/04/04 

Date: Fri, 4 Jun 2004 16:14:10 -0400 (EDT)

On Fri, 4 Jun 2004, Ronen Kfir wrote:
>
> I need to take as an input matrix N*M from stdin & print it as a
> matrix shape, something like:

  First, pick one group and stick to it. Don't multi-post your
message to many different groups. If you *must* post to multiple
groups, then cross-post, like I did in this response (a response
written in response to your question in comp.lang.c, BTW).

  Secondly, no matter what language you're using, you need to
know *what* you're doing before worrying about the *how*. What
kind of input is the user going to be typing? Is he going to
enter

  1 2 3 4 5 6 7 8 9

and you're by magic going to print

  1 2 3
  4 5 6
  7 8 9

or is the user going to have to tell the program how many dimensions
the matrix has, and what size it is, like this?

  4 2
  1 2 3 4 5 6 7 8

and then you would print a 4-by-2 matrix

  1 2 3 4
  5 6 7 8

Maybe the user is going to enter his matrix himself, and use some
special code to indicate that he's done entering rows, like this:

  1 2 3 4 5
  6 7 8 9 10
  11 12 13 14 15
  done

In this last case, would you output

  1 2 3 4 5
  6 7 8 9 10
  11 12 13 14 15

or would your user rather see

   1 2 3 4 5
   6 7 8 9 10
  11 12 13 14 15

In the latter case, should the entries by justified toward the right,
the left, or centered: e.g.,

  1 2 3
  42 567 8
  17 42 725

Should the columns all be equally wide, e.g.

      1 2 65535
      3 4 5

or should they have variable width, e.g.

  1 2 65535
  3 4 5

If the latter, then would it be acceptable to overlap
columns on particularly odd inputs, e.g.

  1 2 1234567890 3 4
  2 456 89 10112 7

If not, then how many spaces between columns? Are hard
tabs okay? (Hint: no. ;) Answer these questions for
yourself, and *then* think about what algorithms you'll
need to implement.

  Once you know not only *what* you're doing, but also
*how* you'll do it (i.e., the algorithms involved), then
you'll finally be ready to start asking questions that
might be topical on comp.lang.c and alt.comp.lang.learn.c-c++.
We deal with the C *language* here, not algorithms; for
algorithm help, try comp.programming.

-Arthur

Relevant Pages

  • Re: print matrix
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