@node asprintf
@subsection @code{asprintf}
@findex asprintf

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/asprintf.html}

Documentation:
@itemize
@item
@ifinfo
@ref{Dynamic Output,,Dynamically Allocating Formatted Output,libc},
@end ifinfo
@ifnotinfo
@url{https://www.gnu.org/software/libc/manual/html_node/Dynamic-Output.html},
@end ifnotinfo
@item
@uref{https://www.kernel.org/doc/man-pages/online/pages/man3/asprintf.3.html,,man asprintf}.
@end itemize

Gnulib module: vasprintf or vasprintf-posix or vasprintf-gnu
@mindex vasprintf
@mindex vasprintf-posix
@mindex vasprintf-gnu

Portability problems fixed by either Gnulib module @code{vasprintf} or @code{vasprintf-posix} or @code{vasprintf-gnu}:
@itemize
@item
This function is missing on some platforms:
AIX 5.1, HP-UX 11, Solaris 10, mingw, MSVC 14.
@end itemize

Portability problems fixed by either Gnulib module @code{vasprintf-posix} or @code{vasprintf-gnu}:
@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:
Cygwin 1.5.24.
@item
This function does not support size specifiers as in C23 (@code{w8},
@code{w16}, @code{w32}, @code{w64}, @code{wf8}, @code{wf16}, @code{wf32},
@code{wf64}) on some platforms:
glibc 2.37, musl libc, macOS 14, FreeBSD 13.2, NetBSD 10.0, OpenBSD 7.9, AIX 7.3, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC, Android 9.0.
@item
printf @code{"%f"}, @code{"%e"}, @code{"%g"} of Infinity and NaN yields an
incorrect result on some platforms:
AIX 7.3, Solaris 11.4.
@item
This function does not support the @samp{a} and @samp{A} directives on some
platforms:
FreeBSD 5.2.1, OpenBSD 4.0, Solaris 11.4, Cygwin 1.5.x.
@item
This function does not support the @samp{b} directive, required by ISO C23,
on some platforms:
glibc 2.34, musl libc, macOS 14, FreeBSD 13.2, NetBSD 10.0, OpenBSD 7.9,
AIX 7.3, HP-UX 11, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC 14, Android 9.0.
@item
This function does not support the @samp{F} directive on some platforms:
NetBSD 3.0, Cygwin 1.5.x.
@item
This function does not support the @samp{ls} directive on some platforms:
OpenBSD 4.0, 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.
@item
This function doesn't support the @code{'} flag at all on some platforms:
mingw without @code{__USE_MINGW_ANSI_STDIO}, MSVC 14.
@item
This function doesn't support the @code{'} flag correctly for integers
(it uses the decimal point instead of the thousands separator!)
on some platforms:
mingw with @code{__USE_MINGW_ANSI_STDIO}.
@item
This function doesn't support the @code{'} flag on some platforms:
NetBSD 3.0, Cygwin 1.5.24.
@item
This function doesn't support the @code{'} flag together with a precision
on an integer argument correctly on some platforms:
glibc 2.36, FreeBSD 14.0, NetBSD 10.0, Solaris 11, Cygwin 3.6.0, Haiku.
@item
This function doesn't support the @code{'} flag correctly in locales where
the thousands separator is a multibyte character on some platforms:
NetBSD 10.0, Solaris 11 OpenIndiana.
@item
This function does not round the argument of the @samp{a} directive correctly
on some platforms:
macOS 14, FreeBSD 14.0, NetBSD 10.0, OpenBSD 7.9, AIX 7.3, Solaris 11.4.
@item
printf @code{"%010f"} of NaN and Infinity yields an incorrect result (padded
with zeroes) on some platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, AIX 7.3, Solaris 11.4, Cygwin 1.5.x.
@item
printf @code{"%#.0x"} or @code{"%#.0X"} with a zero argument yields an
incorrect result (non-empty) on some platforms:
Mac OS X 10.6.
@item
This function produces wrong output for the @samp{lc} directive with a NUL
wide character argument on some platforms:
musl libc 1.2.4.
@item
This function can crash in out-of-memory conditions on some platforms:
FreeBSD 14.0, NetBSD 5.0.
@end itemize

Portability problems fixed by Gnulib module @code{vasprintf-gnu}:
@itemize
@item
This function does not support the @samp{B} directive on some platforms:
glibc 2.34, musl libc, macOS 14, FreeBSD 13.2, NetBSD 10.0, OpenBSD 7.9, AIX 7.3, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC, Android 9.0.
@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
