Recently started hiding "... do" and "while (0);..." in macros to write nicely b...

webstrand · on July 14, 2022

That's pretty cool. It's been a while since I've done C, but couldn't you use a `for` loop instead of a while and perform any necessary cleanup in the "update" section? i.e. https://gcc.godbolt.org/z/jq84jondh

(The condition is optimized away by the big three: msvc, clang, and gcc)

billforsternz · on July 14, 2022

Looks good. I wonder why this trick is invariably implemented with "do {" and "} while (0)" and never with "if(1) {" and "} else" ?

taspeotis · on July 14, 2022

I think in part because do … while expects a ; at the end so you are obliged to provide one, which makes the macro feel more like a “real” function call.

if … else {} you could omit the ;

billforsternz · on July 14, 2022

Good point, thank you. The while (0) demands the expected ; The trailing else hopes for the expected ; but would tolerate a wide range of nonsense instead.

ttoinou · on July 14, 2022

Why do you need to start with while (0); ?

calahad · on July 14, 2022

https://bruceblinn.com/linuxinfo/DoWhile.html

ttoinou · on July 23, 2022

  #define end_element()    \
    while (0);     \
    do {      \
   if (xmlTextWriterEndElement (xo) == -1) { \
     xml_error ("xmlTextWriterEndElement"); \
   }      \
    } while (0)

Talking about the first while (0);