Section: POSIX Programmer's Manual (3P)
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.
--- convert a wide-character string to a character string
size_t wcstombs(char *restrict s, const wchar_t *restrict pwcs,
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.1-2008 defers to the ISO C standard.
function shall convert the sequence of wide-character codes that are
in the array pointed to by
into a sequence of characters that begins in the initial shift state
and store these characters into the array pointed to by
stopping if a character would exceed the limit of
total bytes or if a null byte is stored. Each wide-character code
shall be converted as if by a call to
except that the shift state of
shall not be affected.
The behavior of this function shall be affected by the
category of the current locale.
No more than
bytes shall be modified in the array pointed to by
If copying takes place between objects that overlap, the behavior is
is a null pointer,
shall return the length required to convert the entire array
regardless of the value of
but no values are stored.
If a wide-character code is encountered that does not correspond to a
valid character (of one or more bytes each),
shall return (size_t
shall return the number of bytes stored in the character array, not
including any terminating null byte. The array shall not be
null-terminated if the value returned is
function shall fail if:
A wide-character code does not correspond to a valid character.
The following sections are informative.
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
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