@node snprintf
@subsection @code{snprintf}
@findex snprintf

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

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

Portability problems fixed by either Gnulib module @code{snprintf} or @code{snprintf-posix} or @code{snprintf-gnu}:
@itemize
@item
This function is missing on some platforms:
MSVC 14.
@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.
@item
This function does not return a byte count as specified in C99 on some
platforms:
HP-UX 11, Solaris 9, mingw.
@end itemize

Portability problems fixed by either Gnulib module @code{snprintf-posix} or @code{snprintf-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:
AIX 5.1, HP-UX 11.23, Solaris 9, Cygwin 1.5.24, old mingw, MSVC 9.
@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 7.5, AIX 7.3, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC, Android 9.0.
@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 7.3, Solaris 11.4, mingw, MSVC 14.
@item
This function does not support the @samp{a} and @samp{A} directives on some
platforms:
FreeBSD 5.2.1, OpenBSD 4.0, AIX 5.2, HP-UX 11,
Solaris 11.4, Cygwin 1.5.x, mingw, MSVC 14.
@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 7.5,
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, AIX 5.1, HP-UX 11.23, Solaris 9,
Cygwin 1.5.x, mingw, MSVC 14.
@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 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:
macOS 14, FreeBSD 14.0, NetBSD 10.0, OpenBSD 7.5, AIX 7.3, Solaris 11.4.
@item
printf @code{"%010f"} of NaN and Infinity yields an incorrect result (padded
with zeroes, or wrong capitalization) on some platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, AIX 7.3, Solaris 11.4, Cygwin 1.5.x, mingw, MSVC/clang.
@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 does not support precisions larger than 512 or 1024 in integer,
floating-point and pointer output on some platforms:
AIX 7.1, Solaris 10/x86, mingw, MSVC/clang.
@item
This function mishandles large floating point precisions
(for example, formatting 1.0 with @samp{"%.511f"})
on some platforms:
Solaris 10.
@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.
@item
This function does not truncate the result as specified in C99 on some platforms:
mingw, MSVC 14.
@item
This function does not fully support the @samp{n} directive on some platforms:
HP-UX 11, mingw.
@end itemize

Portability problems fixed by Gnulib module @code{snprintf-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 7.5, AIX 7.3, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC, Android 9.0.
@end itemize

@mindex printf-with-n-directive
Portability problems fixed by either Gnulib module @code{snprintf-posix} or @code{snprintf-gnu}
and additionally the Gnulib module @code{printf-with-n-directive}:
@itemize
@item
This function does not support the @samp{n} directive on some platforms:
glibc when used with @code{_FORTIFY_SOURCE >= 2} (set by default on Ubuntu),
macOS 14, OpenBSD, MSVC 14, Android.
@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.
@item
Formatting noncanonical @samp{long double} numbers produces
nonmeaningful results on some platforms:
glibc and others, on x86, x86_64, IA-64 CPUs.
@item
When formatting an integer with grouping flag, this function inserts thousands
separators even in the "C" locale on some platforms:
NetBSD 5.1.
@end itemize
