Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #149846
| From | T <T@invalid.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: what does # mean? |
| Date | 2020-02-08 00:10 -0800 |
| Organization | A noiseless patient Spider |
| Message-ID | <r1lqec$71e$1@dont-email.me> (permalink) |
| References | <r1l2nb$n2s$1@dont-email.me> <6dcd71aa-6b41-4193-8d53-813dbc198686@googlegroups.com> |
On 2020-02-07 20:04, James Kuyper wrote: > On Friday, February 7, 2020 at 8:26:13 PM UTC-5, T wrote: >> Hi All >> >> what does the "#" in >> >> #define GDK_SELECTION_SECONDARY GDK_MAKE_ATOM (2) >> >> mean? >> >> And is "define" what others call a constant? > > The # does not mean anything on it's own, but every preprocessing > directive starts with #. #define is one kind of preprocessing directive. > It defines a macro, in this case GDK_SELECTION_SECONDARY. Associated > with a macro is its replacement text, in this case "GDK_MAKE_ATOM (2)". > After a macro is defined, subsequent occurrences of the macro get > replaced with the replacement text for that macro. Therefore, if you had > a line like > > int n = GDK_SELECTION_SECONDARY; > > Then after replacement, it would say: > > int n = GDK_MAKE_ATOM (2); > > There are some moderately complicated rules governing special cases with > macros, but at your level the only important thing you need to know is > that the macro gets replaced by its replacement text. The expansion of a > macro can be a constant, but this is not an example. The following is an > example: > > #define MONTHS_PER_YEAR 12 > Thank you!
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
what does # mean? T <T@invalid.invalid> - 2020-02-07 17:26 -0800
Re: what does # mean? luser droog <luser.droog@gmail.com> - 2020-02-07 17:51 -0800
Re: what does # mean? T <T@invalid.invalid> - 2020-02-07 18:00 -0800
Re: what does # mean? T <T@invalid.invalid> - 2020-02-07 18:00 -0800
Re: what does # mean? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-07 20:04 -0800
Re: what does # mean? T <T@invalid.invalid> - 2020-02-08 00:10 -0800
Re: what does # mean? scott@slp53.sl.home (Scott Lurndal) - 2020-02-08 18:35 +0000
Re: what does # mean? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-08 13:38 -0800
csiph-web