'\" t .\" Copyright (c) Bruno Haible .\" .\" SPDX-License-Identifier: GPL-2.0-or-later .\" .\" References consulted: .\" GNU glibc-2 source code and manual .\" Dinkumware C library reference http://www.dinkumware.com/ .\" OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html .\" .TH wcsnrtombs 3 2023-07-20 "Linux man-pages 6.05.01" .SH NAME wcsnrtombs \- convert a wide-character string to a multibyte string .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .B #include .PP .BI "size_t wcsnrtombs(char " dest "[restrict ." len "], \ const wchar_t **restrict " src , .BI " size_t " nwc ", size_t " len ", \ mbstate_t *restrict " ps ); .fi .PP .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .PP .BR wcsnrtombs (): .nf Since glibc 2.10: _POSIX_C_SOURCE >= 200809L Before glibc 2.10: _GNU_SOURCE .fi .SH DESCRIPTION The .BR wcsnrtombs () function is like the .BR wcsrtombs (3) function, except that the number of wide characters to be converted, starting at .IR *src , is limited to .IR nwc . .PP If .I dest is not NULL, the .BR wcsnrtombs () function converts at most .I nwc wide characters from the wide-character string .I *src to a multibyte string starting at .IR dest . At most .I len bytes are written to .IR dest . The shift state .I *ps is updated. The conversion is effectively performed by repeatedly calling .IR "wcrtomb(dest, *src, ps)" , as long as this call succeeds, and then incrementing .I dest by the number of bytes written and .I *src by one. The conversion can stop for three reasons: .IP \[bu] 3 A wide character has been encountered that can not be represented as a multibyte sequence (according to the current locale). In this case, .I *src is left pointing to the invalid wide character, .I (size_t)\ \-1 is returned, and .I errno is set to .BR EILSEQ . .IP \[bu] .I nwc wide characters have been converted without encountering a null wide character (L\[aq]\e0\[aq]), or the length limit forces a stop. In this case, .I *src is left pointing to the next wide character to be converted, and the number of bytes written to .I dest is returned. .IP \[bu] The wide-character string has been completely converted, including the terminating null wide character (which has the side effect of bringing back .I *ps to the initial state). In this case, .I *src is set to NULL, and the number of bytes written to .IR dest , excluding the terminating null byte (\[aq]\e0\[aq]), is returned. .PP If .I dest is NULL, .I len is ignored, and the conversion proceeds as above, except that the converted bytes are not written out to memory, and that no destination length limit exists. .PP In both of the above cases, if .I ps is NULL, a static anonymous state known only to the .BR wcsnrtombs () function is used instead. .PP The programmer must ensure that there is room for at least .I len bytes at .IR dest . .SH RETURN VALUE The .BR wcsnrtombs () function returns the number of bytes that make up the converted part of multibyte sequence, not including the terminating null byte. If a wide character was encountered which could not be converted, .I (size_t)\ \-1 is returned, and .I errno set to .BR EILSEQ . .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lb lb lbx l l l. Interface Attribute Value T{ .na .nh .BR wcsnrtombs () T} Thread safety T{ .na .nh MT-Unsafe race:wcsnrtombs/!ps T} .TE .sp 1 .SH STANDARDS POSIX.1-2008. .SH NOTES The behavior of .BR wcsnrtombs () depends on the .B LC_CTYPE category of the current locale. .PP Passing NULL as .I ps is not multithread safe. .SH SEE ALSO .BR iconv (3), .BR mbsinit (3), .BR wcsrtombs (3)