Format
#include <stdarg.h>
#include <stdio.h>
#include <wchar.h>
int vfwprintf(FILE *stream, const wchar_t *format, va_list arg);Language Level: ANSI
Threadsafe: Yes.
Locale Sensitive: The behavior of this function might be affected by the LC_CTYPE and LC_NUMERIC categories of the current locale. The behavior might also be affected by the LC_UNI_CTYPE and LC_UNI_NUMERIC categories of the current locale if LOCALETYPE(*LOCALEUCS2) or LOCALETYPE(*LOCALEUTF) is specified on the compilation command. This function is not available when LOCALETYPE(*CLD) is specified on the compilation command. For more information, see Understanding CCSIDs and Locales.
Integrated File System Interface: This function is not available when SYSIFCOPT(*NOIFSIO) is specified on the compilation command.
Wide Character Function: See Wide Characters for more information.
Description
The vfwprintf() function is equivalent to the fwprintf() function, except that the variable argument list is replaced by arg, which the va_start macro (and possibly subsequent va_arg calls) will have initialized. The vfwprintf() function does not invoke the va_end macro.
Because the functions vfwprintf(), vswprintf(), and vwprintf()invoke the va_arg macro, the value of arg after the return is unspecified.
Return Value
The vfwprintf() function returns the number of wide characters that are written to the output buffer, not counting the ending null wide character or a negative value if an error was encountered. If n or more wide characters are requested to be written, a negative value is returned.
Example that uses vfwprintf()
This example prints the wide character a to a file. The printing is done from the vout() function, which takes a variable number of arguments and uses vfwprintf() to print them to a file.
#include <wchar.h>
#include <stdarg.h>
#include <locale.h>
void vout (FILE *stream, wchar_t *fmt, ...);
const char ifs_path [] = "tmp/myfile";
int main(void) {
FILE *stream;
wchar_t format [] = L"%lc";
setlocale(LC_ALL, "POSIX");
if ((stream = fopen (ifs_path, "w")) == NULL) {
printf("Could not open file.\n");
return (-1);
}
vout (stream, format, L'a');
fclose (stream);
/***********************************************
The contents of output file tmp/myfile.dat should
be a wide char 'a' which in the "POSIX" locale
is '0081'x.
*/
return (0);
}
void vout (FILE *stream, wchar_t *fmt, ...)
{
va_list arg_ptr;
va_start (arg_ptr, fmt);
vfwprintf (stream, fmt, arg_ptr);
va_end (arg_ptr);
} Related Information