digitalmars.D.learn - D f(...) to C f(va_list)
- Denis R (4/4) May 13 2005 Hello,
- Ben Hinkle (9/15) May 13 2005 If the C function is something like
- Denis R (15/37) May 14 2005 This example doest work :/ I get segfault right on that vfprintf call
- Thomas Kuehne (12/24) May 14 2005 -----BEGIN PGP SIGNED MESSAGE-----
- Denis R (6/40) May 14 2005 :D
- Brian White (15/29) May 16 2005 I believe that D is passing your argument string as a "char[]" and not a...
- DenisR (5/34) May 20 2005 Hey,
Hello, Im having trouble with sending variable number of args that my D funcs gets, into a C func, that takes va_list as one of the args. Im not too sure how this is suppose to be done. I guess in same way as its done in C, but using those std.c.stdarg's templates ? Anyone could give me a quick example ? Im not good with D yet :)
May 13 2005
"Denis R" <denis_r telkomsa.net> wrote in message news:20050514021847.3425372d.denis_r telkomsa.net...Hello, Im having trouble with sending variable number of args that my D funcs gets, into a C func, that takes va_list as one of the args. Im not too sure how this is suppose to be done. I guess in same way as its done in C, but using those std.c.stdarg's templates ? Anyone could give me a quick example ? Im not good with D yet :)If the C function is something like extern (C) vfoo(va_list args); then you should be able to do void bar(...) { vfoo(_argptr); } If not then something is fishy.
May 13 2005
On Fri, 13 May 2005 22:00:19 -0400 "Ben Hinkle" <ben.hinkle gmail.com> wrote:"Denis R" <denis_r telkomsa.net> wrote in message news:20050514021847.3425372d.denis_r telkomsa.net...This example doest work :/ I get segfault right on that vfprintf call extern (C) int vfprintf(FILE *stream, char *format, va_list ap); void myfunc(char *fmt, ...) { puts("hello"); vfprintf(stderr, fmt, _argptr); } int main (char[][] args) { myfunc("%s\n", "Bla bla blas"); return (0); } (By the way, why cant I have const char* ptr ? I thought it was allowed. )Hello, Im having trouble with sending variable number of args that my D funcs gets, into a C func, that takes va_list as one of the args. Im not too sure how this is suppose to be done. I guess in same way as its done in C, but using those std.c.stdarg's templates ? Anyone could give me a quick example ? Im not good with D yet :)If the C function is something like extern (C) vfoo(va_list args); then you should be able to do void bar(...) { vfoo(_argptr); } If not then something is fishy.
May 14 2005
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Denis R schrieb am Sat, 14 May 2005 09:25:11 +0200:This example doest work :/ I get segfault right on that vfprintf call extern (C) int vfprintf(FILE *stream, char *format, va_list ap); void myfunc(char *fmt, ...) { puts("hello"); vfprintf(stderr, fmt, _argptr); } int main (char[][] args) { myfunc("%s\n", "Bla bla blas");myfunc("%.*s\n", "Bla bla blas"); or myfunc("%s\n", std.string.toStringz("Bla bla blas"));return (0); }Thomas -----BEGIN PGP SIGNATURE----- iD8DBQFChcby3w+/yD4P9tIRAggXAJ9BWCGz7o0tM0wacjv8s0UB0Rw5ZwCgpIBg SBmuLgYtLINHFTazdqWPkUU= =vxSp -----END PGP SIGNATURE-----
May 14 2005
Denis R <denis_r telkomsa.net> :D That seems to work. Thank you. Will try now on my actual code. On Sat, 14 May 2005 11:37:54 +0200 Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> wrote:-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Denis R schrieb am Sat, 14 May 2005 09:25:11 +0200:This example doest work :/ I get segfault right on that vfprintf call extern (C) int vfprintf(FILE *stream, char *format, va_list ap); void myfunc(char *fmt, ...) { puts("hello"); vfprintf(stderr, fmt, _argptr); } int main (char[][] args) { myfunc("%s\n", "Bla bla blas");myfunc("%.*s\n", "Bla bla blas"); or myfunc("%s\n", std.string.toStringz("Bla bla blas"));return (0); }Thomas -----BEGIN PGP SIGNATURE----- iD8DBQFChcby3w+/yD4P9tIRAggXAJ9BWCGz7o0tM0wacjv8s0UB0Rw5ZwCgpIBg SBmuLgYtLINHFTazdqWPkUU= =vxSp -----END PGP SIGNATURE-----
May 14 2005
This example doest work :/ I get segfault right on that vfprintf call extern (C) int vfprintf(FILE *stream, char *format, va_list ap); void myfunc(char *fmt, ...) { puts("hello"); vfprintf(stderr, fmt, _argptr); } int main (char[][] args) { myfunc("%s\n", "Bla bla blas"); return (0); }I believe that D is passing your argument string as a "char[]" and not a "char*". The former is actually two values, a element count and a pointer (in that order). Thus, the %s tries to dereference the element count as a pointer and goes in to neverland. You could try: cast(char*)"Bla bla blas" (I haven't tried it -- I'm just speculating).(By the way, why cant I have const char* ptr ? I thought it was allowed. )No, D uses as a scope rather than as an attribute (or some wording like that). The upshot is that it can't be used to describe constness of something being pointed to. Personally, I think this is a grave deficiency in the language, but I'm just a novice at D and may simply not undestand the genius of the choice. <grin> Brian ( bcwhite precidia.com ) ------------------------------------------------------------------------------- In theory, theory and practice are the same. In practice, they're not.
May 16 2005
Hey, I did try the way you suggest. But the cast did not work. Did you see the second reply I got ? You just specify "%*.s", and that kind of makes D's char[] into the C's char* :) In article <d6als4$28lj$1 digitaldaemon.com>, Brian White says...This example doest work :/ I get segfault right on that vfprintf call extern (C) int vfprintf(FILE *stream, char *format, va_list ap); void myfunc(char *fmt, ...) { puts("hello"); vfprintf(stderr, fmt, _argptr); } int main (char[][] args) { myfunc("%s\n", "Bla bla blas"); return (0); }I believe that D is passing your argument string as a "char[]" and not a "char*". The former is actually two values, a element count and a pointer (in that order). Thus, the %s tries to dereference the element count as a pointer and goes in to neverland. You could try: cast(char*)"Bla bla blas" (I haven't tried it -- I'm just speculating).(By the way, why cant I have const char* ptr ? I thought it was allowed. )No, D uses as a scope rather than as an attribute (or some wording like that). The upshot is that it can't be used to describe constness of something being pointed to. Personally, I think this is a grave deficiency in the language, but I'm just a novice at D and may simply not undestand the genius of the choice. <grin> Brian ( bcwhite precidia.com ) ------------------------------------------------------------------------------- In theory, theory and practice are the same. In practice, they're not.
May 20 2005