vfprintf3p
Format output of a stdarg argument list
Usage
#include <stdarg.h> #include <stdio.h>
int vdprintf(int fildes, const char *restrict format, va_list ap); int vfprintf(FILE *restrict stream, const char *restrict format,
va_list ap); int vprintf(const char *restrict format, va_list ap); int vsnprintf(char *restrict s, size_t n, const char *restrict format,
va_list ap); int vsprintf(char *restrict s, const char *restrict format, va_list ap);
Prolog
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
Overview
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard.
The vdprintf(), vfprintf(), vprintf(), vsnprintf(), and vsprintf() functions shall be equivalent to the dprintf(), fprintf(), printf(), snprintf(), and sprintf() functions respectively, except that instead of being called with a variable number of arguments, they are called with an argument list as defined by <stdarg.h>.
These functions shall not invoke the va_end macro. As these functions invoke the va_arg macro, the value of ap after the return is unspecified.
Return value
Refer to fprintf().
Errors
Refer to fprintf().
The following sections are informative.
Examples
None.
Application usage
Applications using these functions should call va_end(ap) afterwards to clean up.
Rationale
None.
Future directions
None.