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[asterisk-dev] OT: C problems with access to "struct ast_fra

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wirtz at dfn.de
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Posted: Sun May 24, 2009 6:42 pm Post subject: [asterisk-dev] OT: C problems with access to "struct ast_fra

Hi all, sorry for this OT message but since my last Debian update I have some trouble to access the data member of the structast_frame: struct ast_frame { ... /! Pointer to actual data / union { void ptr; uint32_t uint32; char pad[8]; } data; ... } Before the update I used something like that: struct ast_frame f=NULL; f=ast_read(chan); if(f->frametype==AST_FRAME_TEXT) { ast_log(AST_CONF_DEBUG,"Text: %s\n",f->data); } Now I get the following error (with gcc version 4.3.3 (Debian 4.3.3-10)) $ cc -I../asterisk/include -I/usr/lib/glib-2.0/include -I/usr/include/glib-2.0 -Wall -c member.c -o member.o member.c: In function 'member_exec': member.c:146: warning: format '%s' expects type 'char ', but argument 6 has type 'union <anonymous>' I tried to cast f->data with (char)... but this won't work, too: ... member.c:146: error: cannot convert to a pointer type member.c:146: warning: reading through null pointer (argument 6) member.c:147: error: cannot convert to a pointer type ... Hell, what am I doing wrong? Regards, Holger _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev

arkadi.shishlov at gmail.
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Posted: Sun May 24, 2009 8:04 pm Post subject: [asterisk-dev] OT: C problems with access to "struct ast_fra

Holger Wirtz wrote:

Quote:

struct ast_frame {
...
/*! Pointer to actual data */
union { void *ptr; uint32_t uint32; char pad[8]; } data;

use f->data.ptr

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moises.silva at gmail.com
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Posted: Sun May 24, 2009 8:09 pm Post subject: [asterisk-dev] OT: C problems with access to "struct ast_fra

Quote:

Before the update I used something like that:

struct ast_frame *f=NULL;
f=ast_read(chan);
if(f->frametype==AST_FRAME_TEXT) {
ast_log(AST_CONF_DEBUG,"Text: %s\n",f->data);
}

You need to read this: http://www.crasseux.com/books/ctutorial/union.html

And use the ptr member of the union.

struct ast_frame *f=NULL;
f=ast_read(chan);
if(f->frametype==AST_FRAME_TEXT) {
ast_log(AST_CONF_DEBUG,"Text: %s\n",f->data.ptr);
}

In the future you may want to take a look at how other code makes use
of frames, is not that hard.

Moy

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wirtz at dfn.de
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Posted: Mon May 25, 2009 5:19 am Post subject: [asterisk-dev] OT: C problems with access to "struct ast_fra

Arkadi, Moises,

Arkadi Shishlov wrote:

Quote:

Holger Wirtz wrote:
> struct ast_frame {
> ...
> /*! Pointer to actual data */
> union { void *ptr; uint32_t uint32; char pad[8]; } data;

use f->data.ptr

Ahhh! I am such an idiot... ok, I see what I was doing wrong. Sorry for
contacting the list with such a stupid question!

Thanks, Holger

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tilghman at mail.jeffandt
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Posted: Tue May 26, 2009 1:00 pm Post subject: [asterisk-dev] OT: C problems with access to "struct ast_fra

On Sunday 24 May 2009 14:25:59 Holger Wirtz wrote:

Quote:

Hi all,

sorry for this OT message but since my last Debian update I have some
trouble to access the data member of the structast_frame:

struct ast_frame {
...
/*! Pointer to actual data */
union { void *ptr; uint32_t uint32; char pad[8]; } data;
...
}

Before the update I used something like that:

struct ast_frame *f=NULL;
f=ast_read(chan);
if(f->frametype==AST_FRAME_TEXT) {
ast_log(AST_CONF_DEBUG,"Text: %s\n",f->data);
}

Now I get the following error (with gcc version 4.3.3 (Debian 4.3.3-10))

$ cc -I../asterisk/include -I/usr/lib/glib-2.0/include
-I/usr/include/glib-2.0 -Wall -c member.c -o member.o
member.c: In function 'member_exec':
member.c:146: warning: format '%s' expects type 'char *', but argument 6
has type 'union <anonymous>'

I tried to cast f->data with (char*)... but this won't work, too:

Right, so this change was to allow you to access the element as multiple
types, without needing to cast, but you need to add an extra argument onto
the end to get this. So change your invocation of f->data to f->data.ptr
(since you want a pointer). You could also use f->data.uint32, if you wanted
an integer type.

--
Tilghman

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