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.
--- transliterate lowercase characters to uppercase
int _toupper(int c);
macro shall be equivalent to
except that the application shall ensure that the argument
is a lowercase letter.
Upon successful completion,
shall return the uppercase letter corresponding to the argument passed.
No errors are defined.
The following sections are informative.
Applications should use the
function instead of the obsolescent
function may be removed in a future version.
The Base Definitions volume of POSIX.1-2017,
Chapter 7, Locale,
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
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