vwarn(), vwarnx()

Formatted error message (varargs)

Synopsis:

#include <err.h>

void vwarn( const char *fmt, 
            va_list args );

void vwarnx( const char *fmt, 
             va_list args );

fmt: NULL, or a printf()-style string used to format the message.
args: A variable-argument list of the additional arguments, which you must have initialized with the va_start() macro.

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

The err() and warn() family of functions display a formatted error message on stderr. For a comparison of the members of this family, see err().

The vwarn() function produces a message that consists of:

the last component of the program name, followed by a colon and a space
the formatted message, followed by a colon and a space, if the fmt argument isn't NULL
the string associated with the current value of errno
a newline character

The vwarnx() function produces a similar message, except that it doesn't include the string associated with errno. The message consists of: