String Format Function

int vfprintf(FILE* stream, const char *format, va_list argptr);

int vfwprintf(FILE* stream, const wchar_t *format , va_list argptr);

int _vftprintf(FILE* stream, const TCHAR *format, va_list argptr);

Internationalization (I18n) Function Overview

The vfprintf function formats a null-terminated string, using the format argument and the data pointed to by the argptr argument, and outputs it to a stream. The number of bytes written is returned, or -1 if an error occurs.

vfwprintf is the wide character version and returns the number of wide characters written.

_vftprintf is the Windows-only Generic version of the function; with the _MBCS or _UNICODE compiler flags determining its mapping to either vfprintf or vfwprintf.

I18n Issues

Use the appropriate version of the function as required for internationalization support, noting the following:

Prior to calling one of these functions, ensure that the current locale is set properly by calling setlocale, as string formatting is dependent on the LC_NUMERIC locale category. See String Formatting in C and C++ for a discussion on locale-sensitive formatting in internationalized applications.

Recommended Replacements*

ANSI UTF-8	vfprintf
ANSI UTF-16	vfwprintf
Microsoft Windows MBCS	vfprintf
Microsoft Windows Unicode	vfwprintf
Microsoft Windows Generic	_vftprintf

String Format Functions