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Re: Alternative libraries for C, that are efficient

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Hi,

Am 04/12/2012 08:22 PM, schrieb John Reye:
> On Apr 12, 6:13 pm, Jens Gustedt <jens.gust...@loria.fr> wrote:
>> very useful for constructs such as
>>
>> char const* s = strcat(strcpy(malloc(100), "Hello "), "world");
> What's wrong with:
> 
> char * s;
> if ((s = (char *)malloc(100)) == NULL) {
>   fprintf(stderr, "Out of memory\n");
>   exit(1);
> }
> strcpy(s, "Hello ");
> strcat(s, "world");
> 
> Are you trying to tell me that your's will be more efficient.
> Me'thinks not.

Mine is an expression, so it can easily packed in a macro, in the
initializer of a `for`-loop variable, whatever.

>>
>> or
>>
>> char const* t = strcat((char[100]){ "Hello " }, s);
> char *t = (char *)((char[100]){ "Hello " });
> strcat(t, s);

In your's the compound literal makes not much sense, since you give away
the unprotected pointer to it, so it would better be written

char t[100] = { "Hello " };
strcat(t, s);

Mine has the const qualifier on the pointed-to object. How would you
achieve this?

>>> I already know the distination, in the first place.
>>
>> No, not necessarily. The first argument is an expression. This feature
>> avoids to evaluate that expression multiple times.
> 
> Sorry, I don't follow. Could you explain it (perhaps with an example).

If you'd like to use such things in macros (I do) you only want to
evaluate each argument once, because of possible side effects.

#define STRCAT3(X, Y, Z) strcat(strcat((X), (Y)), (Z))

in P99 I have

#define P99_STRCATS(TARG, ...)

that lifts that idea to (almost) any fixed number of arguments.

(Well I am cheating a bit, that one uses stpcpy under the hood to be
more efficient. But the idea is the same.)

Jens

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Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 09:01 -0700
  Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 09:05 -0700
    Re: Alternative libraries for C, that are efficient ImpalerCore <jadill33@gmail.com> - 2012-04-12 09:38 -0700
      Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 11:32 -0700
        Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-12 14:41 -0400
          Re: Alternative libraries for C, that are efficient Willem <willem@toad.stack.nl> - 2012-04-12 18:51 +0000
            Re: Alternative libraries for C, that are efficient nick_keighley_nospam@hotmail.com - 2012-04-13 03:46 -0700
              Re: Alternative libraries for C, that are efficient Willem <willem@toad.stack.nl> - 2012-04-13 14:51 +0000
            Re: Alternative libraries for C, that are efficient Kenneth Brody <kenbrody@spamcop.net> - 2012-04-13 12:38 -0400
              Re: Alternative libraries for C, that are efficient Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-04-15 19:47 +0300
  Re: Alternative libraries for C, that are efficient tom st denis <tom@iahu.ca> - 2012-04-12 09:09 -0700
    Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 11:13 -0700
      Re: Alternative libraries for C, that are efficient tom st denis <tom@iahu.ca> - 2012-04-12 18:20 -0700
  Re: Alternative libraries for C, that are efficient Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-12 18:13 +0200
    Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-12 12:47 -0400
    Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 11:22 -0700
      Re: Alternative libraries for C, that are efficient Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-13 22:37 +0200
        Re: Alternative libraries for C, that are efficient Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-04-15 20:15 +0300
          Re: Alternative libraries for C, that are efficient Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-15 23:30 +0200
  Re: Alternative libraries for C, that are efficient Ben Pfaff <blp@cs.stanford.edu> - 2012-04-12 09:20 -0700
  Re: Alternative libraries for C, that are efficient Noob <root@127.0.0.1> - 2012-04-12 18:34 +0200
    Re: Alternative libraries for C, that are efficient Kaz Kylheku <kaz@kylheku.com> - 2012-04-12 18:00 +0000
      Re: Alternative libraries for C, that are efficient nick_keighley_nospam@hotmail.com - 2012-04-13 03:50 -0700
    Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 11:24 -0700
      Re: Alternative libraries for C, that are efficient Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-04-12 13:08 -0700
  Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-12 12:50 -0400
    Re: Alternative libraries for C, that are efficient John Reye <jononanon@googlemail.com> - 2012-04-12 11:30 -0700
      Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-12 15:55 -0400
  Re: Alternative libraries for C, that are efficient Barry Schwarz <schwarzb@dqel.com> - 2012-04-12 11:41 -0700
    Re: Alternative libraries for C, that are efficient Willem <willem@toad.stack.nl> - 2012-04-12 19:08 +0000
  Re: Alternative libraries for C, that are efficient "BartC" <bc@freeuk.com> - 2012-04-12 21:07 +0100
    Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-12 20:35 -0400
      Re: Alternative libraries for C, that are efficient "BartC" <bc@freeuk.com> - 2012-04-13 11:38 +0100
        Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-13 09:52 -0400
          Re: Alternative libraries for C, that are efficient "BartC" <bc@freeuk.com> - 2012-04-13 17:56 +0100
      Re: Alternative libraries for C, that are efficient Kenneth Brody <kenbrody@spamcop.net> - 2012-04-13 12:56 -0400
        Re: Alternative libraries for C, that are efficient James Kuyper <jameskuyper@verizon.net> - 2012-04-13 14:48 -0400
          Re: Alternative libraries for C, that are efficient Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-04-14 07:22 -0700
  Re: Alternative libraries for C, that are efficient Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-12 21:23 -0400
    Re: Alternative libraries for C, that are efficient Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2012-04-13 16:52 +0000
  Re: Alternative libraries for C, that are efficient Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-13 23:24 +0200

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