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.
#include <stdio.h> #include <wchar.h> wint_t btowc(int c);
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.1-2017 defers to the ISO C standard.
The btowc() function shall determine whether c constitutes a valid (one-byte) character in the initial shift state.
The behavior of this function shall be affected by the LC_CTYPE category of the current locale.
The btowc() function shall return WEOF if c has the value EOF or if (unsigned char) c does not constitute a valid (one-byte) character in the initial shift state. Otherwise, it shall return the wide-character representation of that character.
In the POSIX locale, btowc() shall not return WEOF if c has a value in the range 0 to 255 inclusive.
No errors are defined.
The following sections are informative.
The Base Definitions volume of POSIX.1-2017, <stdio.h>, <wchar.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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 http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .
fwprintf(3p), wchar.h(0p), wctob(3p).