Re: how to make a macro work as a single line if stmt without braces

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Sujet : Re: how to make a macro work as a single line if stmt without braces
De : andreytarasevich (at) *nospam* hotmail.com (Andrey Tarasevich)
Groupes : comp.lang.c
Date : 21. Sep 2024, 20:17:15
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <vcn63s$1n207$1@dont-email.me>
References : 1
User-Agent : Mozilla Thunderbird
On 09/21/24 12:35 AM, Mark Summerfield wrote:
I have this macro:
 #define WARN(...)                                       \
     do {                                                \
         fprintf(stderr, "%s#%d: ", __FILE__, __LINE__); \
         fprintf(stderr, __VA_ARGS__);                   \
     } while (0);
 which I use like this:
 total++;
if (failed) {
     WARN("failed because...");
} else
     ok++;
 I would prefer to be able to write this instead:
 total++;
if (failed)
     WARN("failed because...");
else
     ok++;
 but doing so results in a compiler error:
 error: 'else' without a previous 'if'
The whole idea of `do { ... } while(false)` idiom for writing complex macros is based on _not_ including that `;` after `while(false)` into the macro. Meanwhile, you botched the whole thing by adding that `;` there.
Remove the trailing `;` from the macro and everything will work as you want it to.
--
Best regards,
Andrey

Date Sujet#  Auteur
21 Sep 24 * how to make a macro work as a single line if stmt without braces61Mark Summerfield
21 Sep 24 +- Re: how to make a macro work as a single line if stmt without braces1Lawrence D'Oliveiro
21 Sep 24 +* Re: how to make a macro work as a single line if stmt without braces50David Brown
21 Sep 24 i`* Re: how to make a macro work as a single line if stmt without braces49Andrey Tarasevich
21 Sep 24 i +- Re: how to make a macro work as a single line if stmt without braces1Bart
21 Sep 24 i +- Re: how to make a macro work as a single line if stmt without braces1Opus
21 Sep 24 i +* Re: how to make a macro work as a single line if stmt without braces5Keith Thompson
22 Sep 24 i i`* Re: how to make a macro work as a single line if stmt without braces4Andrey Tarasevich
22 Sep 24 i i +- Re: how to make a macro work as a single line if stmt without braces1Keith Thompson
22 Sep 24 i i +- Re: how to make a macro work as a single line if stmt without braces1David Brown
27 Sep 24 i i `- Re: how to make a macro work as a single line if stmt without braces1Tim Rentsch
22 Sep 24 i +* Re: how to make a macro work as a single line if stmt without braces25David Brown
22 Sep 24 i i`* Re: how to make a macro work as a single line if stmt without braces24Kaz Kylheku
22 Sep 24 i i +* Re: how to make a macro work as a single line if stmt without braces21Bart
22 Sep 24 i i i+* Re: how to make a macro work as a single line if stmt without braces14Michael S
22 Sep 24 i i ii+- Re: how to make a macro work as a single line if stmt without braces1Bart
24 Sep 24 i i ii`* Re: how to make a macro work as a single line if stmt without braces12Tim Rentsch
24 Sep 24 i i ii +* Re: how to make a macro work as a single line if stmt without braces5Andrey Tarasevich
24 Sep 24 i i ii i+- Re: how to make a macro work as a single line if stmt without braces1David Brown
24 Sep 24 i i ii i+* Re: how to make a macro work as a single line if stmt without braces2Bart
24 Sep 24 i i ii ii`- Re: how to make a macro work as a single line if stmt without braces1Keith Thompson
27 Sep 24 i i ii i`- Re: how to make a macro work as a single line if stmt without braces1Tim Rentsch
24 Sep 24 i i ii `* Re: how to make a macro work as a single line if stmt without braces6Bart
24 Sep 24 i i ii  +* Re: how to make a macro work as a single line if stmt without braces2Keith Thompson
24 Sep 24 i i ii  i`- Re: how to make a macro work as a single line if stmt without braces1Bart
24 Sep 24 i i ii  `* Re: how to make a macro work as a single line if stmt without braces3Kaz Kylheku
24 Sep 24 i i ii   `* Re: how to make a macro work as a single line if stmt without braces2Bart
25 Sep 24 i i ii    `- Re: how to make a macro work as a single line if stmt without braces1Kaz Kylheku
22 Sep 24 i i i`* Re: how to make a macro work as a single line if stmt without braces6Keith Thompson
23 Sep 24 i i i `* Re: how to make a macro work as a single line if stmt without braces5David Brown
23 Sep 24 i i i  `* Re: how to make a macro work as a single line if stmt without braces4Richard Harnden
23 Sep 24 i i i   `* Re: how to make a macro work as a single line if stmt without braces3David Brown
23 Sep 24 i i i    `* Re: how to make a macro work as a single line if stmt without braces2Richard Harnden
23 Sep 24 i i i     `- Re: how to make a macro work as a single line if stmt without braces1David Brown
22 Sep 24 i i +- Modern text editor - 'bout time someone paid attention to keeping the thread title relevant!!! (Was: how to make a macro work as a single line if stmt without braces)1Kenny McCormack
22 Sep 24 i i `- Re: how to make a macro work as a single line if stmt without braces1David Brown
28 Sep 24 i `* Re: how to make a macro work as a single line if stmt without braces16Tim Rentsch
28 Sep 24 i  +* Re: how to make a macro work as a single line if stmt without braces5Michael S
29 Sep 24 i  i`* Re: how to make a macro work as a single line if stmt without braces4Tim Rentsch
29 Sep 24 i  i `* Re: how to make a macro work as a single line if stmt without braces3Michael S
30 Sep 24 i  i  +- Re: how to make a macro work as a single line if stmt without braces1Tim Rentsch
30 Sep 24 i  i  `- Re: how to make a macro work as a single line if stmt without braces1Alan Mackenzie
29 Sep 24 i  `* Re: how to make a macro work as a single line if stmt without braces10Andrey Tarasevich
29 Sep 24 i   `* Re: how to make a macro work as a single line if stmt without braces9Tim Rentsch
29 Sep 24 i    `* Re: how to make a macro work as a single line if stmt without braces8Andrey Tarasevich
29 Sep 24 i     +- Re: how to make a macro work as a single line if stmt without braces1Michael S
30 Sep 24 i     +* Re: how to make a macro work as a single line if stmt without braces3Keith Thompson
30 Sep 24 i     i`* Re: how to make a macro work as a single line if stmt without braces2Kaz Kylheku
30 Sep 24 i     i `- Re: how to make a macro work as a single line if stmt without braces1Janis Papanagnou
30 Sep 24 i     +- Re: how to make a macro work as a single line if stmt without braces1Tim Rentsch
30 Sep 24 i     +- Re: how to make a macro work as a single line if stmt without braces1Kaz Kylheku
30 Sep 24 i     `- Re: how to make a macro work as a single line if stmt without braces1David Brown
21 Sep 24 +* Re: how to make a macro work as a single line if stmt without braces2Bart
21 Sep 24 i`- Re: how to make a macro work as a single line if stmt without braces1Mark Summerfield
21 Sep 24 +* Re: how to make a macro work as a single line if stmt without braces2Ike Naar
21 Sep 24 i`- Re: how to make a macro work as a single line if stmt without braces1Keith Thompson
21 Sep 24 +* Re: how to make a macro work as a single line if stmt without braces2Tim Rentsch
22 Sep 24 i`- Re: how to make a macro work as a single line if stmt without braces1Keith Thompson
21 Sep 24 +- Re: how to make a macro work as a single line if stmt without braces1Andrey Tarasevich
21 Sep 24 `* Re: how to make a macro work as a single line if stmt without braces2Blue-Maned_Hawk
24 Sep 24  `- Re: how to make a macro work as a single line if stmt without braces1Tim Rentsch

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