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Name

MT-Level

Synopsis

#include <stdarg.h>
#include <pfmt.h>

int vpfmt(FILE *stream, long flags, char *format, va_list ap);

Description

The <stdarg.h> header file defines the type va_list and a set of macros for advancing through a list of arguments whose number and types may vary. The argument ap to vpfmt() is of type va_list. This argument is used with the <stdarg.h> header file macros va_start(), va_arg() and va_end(). [ see va_start(), va_arg(), and va_end() in stdarg(5) ]. The EXAMPLE section below shows their use with vpfmt().

The macro va_alist is used as the parameter list in a function definition as in the function called error() in the example below. The macro va_start(ap, ), where ap is of type va_list, must be called before any attempt to traverse and access unnamed arguments. Calls to va_arg(ap, atype) traverse the argument list. Each execution of va_arg() expands to an expression with the value and type of the next argument in the list ap, which is the same object initialized by va_start. The argument atype is the type that the returned argument is expected to be. The va_end(ap) macro must be invoked when all desired arguments have been accessed. (The argument list in ap can be traversed again if va_start() is called again after va_end().) In the example below, va_arg() is executed first to retrieve the format string passed to error(). The remaining error() arguments, arg1, arg2, ..., are given to vpfmt() in the argument ap.

Return Value

-1

write error to stream.

Example

#include <pfmt.h>
#include <stdarg.h>
/*
 *   error should be called like
 *         error(format, arg1, ...);
 */
void error(...)
{
    va_list ap;
    char *format;
    va_start(ap, );
    format = va_arg(ap, char *);
    (void) vpfmt(stderr, MM_ERROR, format, ap);
    va_end(ap);
    (void) abort();
}

Notes

See Also

Table of Contents

• Name
• MT-Level
• Synopsis
• Description
• Return Value
• Example
• Notes
• See Also