@node obstack_vprintf
@subsection @code{obstack_vprintf}
@findex obstack_vprintf

Documentation:@*
@ifinfo
@ref{Variable Arguments Output,,Variable Arguments Output Functions,libc}.
@end ifinfo
@ifnotinfo
@url{https://www.gnu.org/software/libc/manual/html_node/Variable-Arguments-Output.html}.
@end ifnotinfo

Gnulib module: obstack-printf or obstack-printf-posix

Portability problems fixed by either Gnulib module
@code{obstack-printf} or @code{obstack-printf-posix}:
@itemize
@item
This function is missing on all non-glibc platforms:
macOS 11.1, FreeBSD 13.0, NetBSD 9.0, OpenBSD 6.7, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14, Android 9.0.
@end itemize

Portability problems fixed by Gnulib module @code{obstack-printf-posix}:
@itemize
@item
This function does not support size specifiers as in C99 (@code{hh}, @code{ll},
@code{j}, @code{t}, @code{z}) on some platforms:
AIX 5.1, HP-UX 11.23, IRIX 6.5, Solaris 9, Cygwin 1.5.24, mingw, MSVC 14.
@item
printf of @samp{long double} numbers is unsupported on some platforms:
mingw, MSVC 14.
@item
printf @code{"%f"}, @code{"%e"}, @code{"%g"} of Infinity and NaN yields an
incorrect result on some platforms:
AIX 5.2, Solaris 11.0, mingw, MSVC 14.
@item
This function does not support the @samp{a} and @samp{A} directives on some
platforms:
glibc-2.3.6, NetBSD 9.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
IRIX 6.5, Solaris 11.4, Cygwin 1.5.x, mingw, MSVC 14.
@item
This function does not support the @samp{F} directive on some platforms:
NetBSD 3.0, AIX 5.1, HP-UX 11.23, IRIX 6.5, Solaris 9,
Cygwin 1.5.x, mingw, MSVC 14.
@item
This function does not support the @samp{n} directive on some platforms:
MSVC 14.
@item
This function does not support the @samp{ls} directive on some platforms:
OpenBSD 4.0, IRIX 6.5, Cygwin 1.5.x, Haiku.
@item
This function does not support precisions in the @samp{ls} directive correctly
on some platforms:
Solaris 11.4.
@item
This function does not support format directives that access arguments in an
arbitrary order, such as @code{"%2$s"}, on some platforms:
NetBSD 3.0, mingw, MSVC 14.
@item
This function doesn't support the @code{'} flag on some platforms:
NetBSD 3.0, Cygwin 1.5.24, mingw, MSVC 14.
@item
This function does not round the argument of the @samp{a} directive correctly
on some platforms:
Mac OS X 10.12, FreeBSD 6.1.
@item
printf @code{"%010f"} of NaN and Infinity yields an incorrect result (padded
with zeroes) on some platforms:
Mac OS X 10.5, FreeBSD 13.0, NetBSD 5.0, AIX 5.2, IRIX 6.5, Solaris 11.0, Cygwin 1.5.x, mingw, MSVC/clang.
@item
This function does not support precisions larger than 512 or 1024 in integer,
floating-point and pointer output on some platforms:
Solaris 10/x86, mingw, MSVC/clang.
@item
This function can crash in out-of-memory conditions on some platforms:
FreeBSD 13.0, NetBSD 5.0.
@item
This function does not fully support the @samp{n} directive on some platforms:
HP-UX 11, mingw, MSVC 14.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
The @code{%m} directive is not portable, use @code{%s} mapped to an
argument of @code{strerror(errno)} (or a version of @code{strerror_r})
instead.
@end itemize