_TOUPPER(3POSIX) POSIX Programmer's Manual _TOUPPER(3POSIX)
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.
_toupper — transliterate lowercase characters to uppercase
int _toupper(int c);
The _toupper() macro shall be equivalent to toupper() except that the application shall
ensure that the argument c is a lowercase letter.
Upon successful completion, _toupper() shall return the uppercase letter corresponding to
the argument passed.
No errors are defined.
The following sections are informative.
Applications should use the toupper() function instead of the obsolescent _toupper() func‐
The _toupper() function may be removed in a future version.
The Base Definitions volume of POSIX.1‐2008, Chapter 7, Locale, <ctype.h>
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 discrep‐
ancy 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.unix.org/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 .
IEEE/The Open Group 2013 _TOUPPER(3POSIX)