error, error_at_line, error_message_count, error_on_per_line, error_print_progname — glibc error reporting functions
#include <error.h>
void
error( |
int | status, |
| int | errnum, | |
| const char * | format, | |
...); |
void
error_at_line( |
int | status, |
| int | errnum, | |
| const char * | filename, | |
| unsigned int | linenum, | |
| const char * | format, | |
...); |
extern unsigned int error_message_count; extern int error_one_per_line; extern void (* error_print_progname) (void);
error() is a general error
reporting function. It flushes stdout, and then outputs to stderr the program name, a colon and a
space, the message specified by the printf(3)-style format
string format, and,
if errnum is nonzero,
a second colon and a space followed by the string given by
perror(errnum). Any arguments required for format should follow format in the argument list.
The output is terminated by a newline character.
The program name printed by error() is the value of the global variable
program_invocation_name(3).
program_invocation_name
initially has the same value as main()'s argv[0]. The value of this
variable can be modified to change the output of error().
If status has a
nonzero value, then error()
calls exit(3) to terminate the
program using the given value as the exit status.
The error_at_line() function
is exactly the same as error(),
except for the addition of the arguments filename and linenum. The output produced is
as for error(), except that
after the program name are written: a colon, the value of
filename, a colon,
and the value of linenum. The preprocessor
values __LINE__ and
__FILE__ may be useful when
calling error_at_line(), but
other values can also be used. For example, these arguments
could refer to a location in an input file.
If the global variable error_one_per_line is set nonzero, a
sequence of error_at_line()
calls with the same value of filename and linenum will result in only one
message (the first) being output.
The global variable error_message_count counts the number of
messages that have been output by error() and error_at_line().
If the global variable error_print_progname is assigned the
address of a function (i.e., is not NULL), then that function
is called instead of prefixing the message with the program
name and colon. The function should print a suitable string
to stderr.
These functions and variables are GNU extensions, and should not be used in programs intended to be portable.