C in a Nutshell

Name

vfwprintf, vswprintf, vwprintf

Synopsis

Prints formatted wide-character output using a variable argument list object

#include <stdarg.h>
#include <wchar.h>
intvfwprintf( FILE *fp, const wchar_t * restrict format, va_list argptr );
int vswprintf( wchar_t * restrict s, size_t n,
               const wchar_t * restrict format, va_list argptr );
int vwprintf( const wchar_t * restrict format, va_list argptr );

The functions vfwprintf(), vswprintf(), and vwprintf() are like fwprintf(), swprintf(), and wprintf(), respectively, except that their last argument, argptr, is a variable-argument list object with type va_list. The program must initialize this object by calling the va_start() macro before calling the vfwprintf(), vswprintf(), or vwprintf() function, and must call the va_end() macro after the function returns. Because these functions use the va_arg() macro internally to advance the pointer through the argument list, its value is indeterminate after the vfwprintf(), vswprintf(), or vwprintf() function call has returned.

The vfwprintf() and vwprintf() functions return the number of wide characters written to the output stream, or a negative value if an error occurred. The vswprintf() function returns the number of wide characters written to the output buffer, not counting the terminating null wide character, or a negative value if an encoding error occurred or if the complete output string would have contained more than n wide characters.

Example

See the example for the corresponding byte-character ...