Format
#include <stdarg.h>
#include <stdio.h>
int vfprintf(FILE *stream, const char *format, va_list arg_ptr);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 category 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.
Description
The vfprintf() function formats and writes a series of characters and values to the output stream. The vfprintf() function works just like the fprintf() function, except that arg_ptr points to a list of arguments whose number can vary from call to call in the program. These arguments should be initialized by va_start for each call. In contrast, the fprintf() function can have a list of arguments, but the number of arguments in that list is fixed when you compile the program.
The vfprintf() function converts each entry in the argument list according to the corresponding format specifier in format. The format has the same form and function as the format string for the printf() function.
Return Value
If successful, vfprintf() returns the number of bytes written to stream. If an error occurs, the function returns a negative value.
Example that uses vfprintf()
This example prints out a variable number of strings to the file myfile.
#include <stdarg.h>
#include <stdio.h>
void vout(FILE *stream, char *fmt, ...);
char fmt1 [] = "%s %s %s\n";
int main(void)
{
FILE *stream;
stream = fopen("mylib/myfile", "w");
vout(stream, fmt1, "Sat", "Sun", "Mon");
}
void vout(FILE *stream, char *fmt, ...)
{
va_list arg_ptr;
va_start(arg_ptr, fmt);
vfprintf(stream, fmt, arg_ptr);
va_end(arg_ptr);
}
/****************** Output should be similar to: ****************
Sat Sun Mon
*/Related Information