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Full Discussion: C header file and extern
Top Forums Programming C header file and extern Post 302851813 by tornow on Monday 9th of September 2013 05:20:09 PM
Old 09-09-2013
C header file and extern
In the header file data.h i got:
Code:
const char ack_msg[] = "ack: received your msg\n";

In the code file server.c i got:
Code:
extern const char ack_msg[];

And else it is only used in a function call:
Code:
user$ grep ack_msg *c *h
server.c:extern const char ack_msg[]; 
server.c:    n = write(clientsfd, ack_msg, strlen(ack_msg)); 
data.h:const char ack_msg[] = "ack: received your msg\n"; 
user$

But i get this error when compiling:
Code:
user$ ls
checkr.c  checkr.h  client  client.c  data.h  server.c
user$ gcc checkr.c server.c -Wall -Wextra --pedantic -o server
/tmp/ccdKHyIr.o:(.rodata+0x0): multiple definition of `ack_msg'
/tmp/ccUnDvRc.o:(.rodata+0x0): first defined here
collect2: ld returned 1 exit status
user$

I got data.h included in server.c:
Code:
user$ grep data.h server.c 
#include "data.h"
user$

data.h:
Code:
#ifndef DATA_H
#define DATA_H
const char *progname;
#define BUF_SIZE 512
const char ack_msg[] = "ack: received your msg\n";
#endif

Thanks.
 

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LEARN ABOUT OSX

locale::codes::langvar

Locale::Codes::LangVar(3pm)				 Perl Programmers Reference Guide			       Locale::Codes::LangVar(3pm)

NAME

       Locale::Codes::LangVar - standard codes for language variation identification

SYNOPSIS

	  use Locale::Codes::LangVar;

	  $lvar = code2langvar('acm');		       # $lvar gets 'Mesopotamian Arabic'
	  $code = langvar2code('Mesopotamian Arabic'); # $code gets 'acm'

	  @codes   = all_langvar_codes();
	  @names   = all_langvar_names();

DESCRIPTION

       The "Locale::Codes::LangVar" module provides access to standard codes used for identifying language variations, such as those as defined in
       the IANA language registry.

       Most of the routines take an optional additional argument which specifies the code set to use. If not specified, the default IANA language
       registry codes will be used.

SUPPORTED CODE SETS

       There are several different code sets you can use for identifying language variations. A code set may be specified using either a name, or
       a constant that is automatically exported by this module.

       For example, the two are equivalent:

	  $lvar = code2langvar('en','alpha-2');
	  $lvar = code2langvar('en',LOCALE_CODE_ALPHA_2);

       The codesets currently supported are:

       alpha
	   This is the set of alphanumeric codes from the IANA language registry, such as 'arevela' for Eastern Armenian.

	   This code set is identified with the symbol "LOCALE_LANGVAR_ALPHA".

	   This is the default code set.

ROUTINES

       code2langvar ( CODE [,CODESET] )
       langvar2code ( NAME [,CODESET] )
       langvar_code2code ( CODE ,CODESET ,CODESET2 )
       all_langvar_codes ( [CODESET] )
       all_langvar_names ( [CODESET] )
       Locale::Codes::LangVar::rename_langvar  ( CODE ,NEW_NAME [,CODESET] )
       Locale::Codes::LangVar::add_langvar  ( CODE ,NAME [,CODESET] )
       Locale::Codes::LangVar::delete_langvar  ( CODE [,CODESET] )
       Locale::Codes::LangVar::add_langvar_alias  ( NAME ,NEW_NAME )
       Locale::Codes::LangVar::delete_langvar_alias  ( NAME )
       Locale::Codes::LangVar::rename_langvar_code  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangVar::add_langvar_code_alias  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangVar::delete_langvar_code_alias  ( CODE [,CODESET] )
	   These routines are all documented in the Locale::Codes::API man page.

SEE ALSO

       Locale::Codes
	   The Locale-Codes distribution.

       Locale::Codes::API
	   The list of functions supported by this module.

       http://www.iana.org/assignments/language-subtag-registry
	   The IANA language subtag registry.

AUTHOR

       See Locale::Codes for full author history.

       Currently maintained by Sullivan Beck (sbeck@cpan.org).

COPYRIGHT

	  Copyright (c) 2011-2012 Sullivan Beck

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.16.2							    2012-10-11					       Locale::Codes::LangVar(3pm)
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