Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #17333

Re: stream functions

Show all headers | View raw

On 13.02.2012 11:14, Nick Keighley wrote:
> On Feb 8, 11:16 pm, John Gordon <gor...@panix.com> wrote:
>> In <4f32f90d$0$32645$bbae4...@news.suddenlink.net> "Bill Cunningham" <nos...@nspam.invalid> writes:
> 
> <snip>
> 
>>> Loops is something I've never really caught onto in C.
>>
>> Loops are a basic concept in almost any programming language;
> 
> I think some functional languages manage without them. Certainly Lisp,
> C++, Python programs can be written that don't use loops.
> 

Ah, functional languages! The next big hype after object oriented
languages. Just wait till they notice that functional languages also
aren't the answer to the universe and everything.

>> perhaps you should brush up on them in C.
> 
> to put it mildly! Loops are absolutly fundamental to a language like C.

Theoretically, all loops can be replaced by recursive functions. But
that could become a PITA. For instance, finding x, y and z such that for
a 3D-array a you get a[x][y][z] == c. With loops:

int find_in(int*** a, int* x, int* y, int* z, int c)
{
    for (*x = 0; *x < MAX_X; ++*x)
        for (*y = 0; *y < MAX_Y; ++*y)
            for (*z = 0; *z < MAX_Z; ++*z)
                if (a[*x][*y][*z] == c)
                    return 1;
    return 0;
}

Without loops:

int find_in_z(int*** a, int* x, int* y, int* z, int c)
{
    if (*z >= MAX_Z) return 0;
    if (a[*x][*y][*z] == c) return 1;
    ++*z;
    return find_in_z(a, x, y, z, c);
}

int find_in_y(int*** a, int* x, int* y, int* z, int c)
{
    if (*y >= MAX_Y) return 0;
    if (find_in_z(a, x, y, z, c)) return 1;
    ++*y;
    return find_in_y(a, x, y, z, c);
}

int find_in_x(int*** a, int* x, int* y, int* z, int c)
{
    if (*x >= MAX_X) return 0;
    if (find_in_y(a, x, y, z, c)) return 1;
    ++*x;
    return find_in_x(a, x, y, z, c);
}

int find_in(int*** a, int* x, int* y, int* z, int c)
{
    *x = *y = *z = 0;
    return find_in_x(a, x, y, z, c);
}

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-07 16:50 -0500
  Re: stream functions John Gordon <gordon@panix.com> - 2012-02-07 23:07 +0000
    Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-07 18:31 -0500
      Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-07 18:33 -0500
        Re: stream functions Johann Klammer <klammerj@NOSPAM.a1.net> - 2012-02-08 02:39 +0100
          Re: stream functions Keith Thompson <kst-u@mib.org> - 2012-02-07 18:39 -0800
            Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-07 22:36 -0500
              Re: stream functions Nobody <nobody@nowhere.com> - 2012-02-08 19:43 +0000
          Re: stream functions Barry Schwarz <schwarzb@dqel.com> - 2012-02-07 21:01 -0800
      Re: stream functions John Gordon <gordon@panix.com> - 2012-02-08 15:13 +0000
        Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-08 15:54 -0500
          Re: stream functions John Gordon <gordon@panix.com> - 2012-02-08 21:09 +0000
            Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-08 17:37 -0500
              Re: stream functions John Gordon <gordon@panix.com> - 2012-02-08 23:16 +0000
                Re: stream functions Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-13 02:14 -0800
                Re: stream functions James Kuyper <jameskuyper@verizon.net> - 2012-02-13 05:53 -0500
                Re: stream functions Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-13 03:23 -0800
                Re: stream functions Markus Wichmann <nullplan@gmx.net> - 2012-02-14 21:50 +0100
              Re: stream functions "Heinrich Wolf" <invalid@invalid.invalid> - 2012-02-09 10:45 +0100
                Re: stream functions "Bill Cunningham" <nospam@nspam.invalid> - 2012-02-09 22:37 -0500
          Re: stream functions Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-13 02:17 -0800
      Re: stream functions gordonb.qxgs4@burditt.org (Gordon Burditt) - 2012-02-13 01:03 -0600
        Re: stream functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-02-13 08:23 +0000
        Re: stream functions Keith Thompson <kst-u@mib.org> - 2012-02-13 02:06 -0800
        Re: stream functions David Thompson <dave.thompson2@verizon.net> - 2012-02-18 23:12 -0500

csiph-web