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Full Discussion: C header file and extern
Top Forums Programming C header file and extern Post 302851821 by Corona688 on Monday 9th of September 2013 06:02:02 PM
Old 09-09-2013
You got it exactly backwards.

You should put this in the header file:

Code:
extern const char ack_msg[];


...and this in one and only one C file, call it "data.c" perhaps:

Code:
#include "data.h"

const char ack_msg[] = "ack: received your msg\n";

The string can be used in any C file which does #include "data.h"
This User Gave Thanks to Corona688 For This Post:
 

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ERR_get_error(3)						      OpenSSL							  ERR_get_error(3)

NAME
ERR_get_error, ERR_peek_error, ERR_peek_last_error, ERR_get_error_line, ERR_peek_error_line, ERR_peek_last_error_line, ERR_get_error_line_data, ERR_peek_error_line_data, ERR_peek_last_error_line_data - obtain error code and data SYNOPSIS
#include <openssl/err.h> unsigned long ERR_get_error(void); unsigned long ERR_peek_error(void); unsigned long ERR_peek_last_error(void); unsigned long ERR_get_error_line(const char **file, int *line); unsigned long ERR_peek_error_line(const char **file, int *line); unsigned long ERR_peek_last_error_line(const char **file, int *line); unsigned long ERR_get_error_line_data(const char **file, int *line, const char **data, int *flags); unsigned long ERR_peek_error_line_data(const char **file, int *line, const char **data, int *flags); unsigned long ERR_peek_last_error_line_data(const char **file, int *line, const char **data, int *flags); DESCRIPTION
ERR_get_error() returns the earliest error code from the thread's error queue and removes the entry. This function can be called repeatedly until there are no more error codes to return. ERR_peek_error() returns the earliest error code from the thread's error queue without modifying it. ERR_peek_last_error() returns the latest error code from the thread's error queue without modifying it. See ERR_GET_LIB(3) for obtaining information about location and reason of the error, and ERR_error_string(3) for human-readable error messages. ERR_get_error_line(), ERR_peek_error_line() and ERR_peek_last_error_line() are the same as the above, but they additionally store the file name and line number where the error occurred in *file and *line, unless these are NULL. ERR_get_error_line_data(), ERR_peek_error_line_data() and ERR_get_last_error_line_data() store additional data and flags associated with the error code in *data and *flags, unless these are NULL. *data contains a string if *flags&ERR_TXT_STRING. If it has been allocated by OPENSSL_malloc(), *flags&ERR_TXT_MALLOCED is true. RETURN VALUES
The error code, or 0 if there is no error in the queue. SEE ALSO
err(3), ERR_error_string(3), ERR_GET_LIB(3) HISTORY
ERR_get_error(), ERR_peek_error(), ERR_get_error_line() and ERR_peek_error_line() are available in all versions of SSLeay and OpenSSL. ERR_get_error_line_data() and ERR_peek_error_line_data() were added in SSLeay 0.9.0. ERR_peek_last_error(), ERR_peek_last_error_line() and ERR_peek_last_error_line_data() were added in OpenSSL 0.9.7. 1.0.1e 2013-02-11 ERR_get_error(3)
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