Provided by: manpages-posix-dev_2.16-1_all 
NAME
toupper - transliterate lowercase characters to uppercase
SYNOPSIS
#include <ctype.h> int toupper(int c);
DESCRIPTION
The toupper() function has as a domain a type int, the value of which is representable as an unsigned
char or the value of EOF. If the argument has any other value, the behavior is undefined. If the argument
of toupper() represents a lowercase letter, and there exists a corresponding uppercase letter (as
defined by character type information in the program locale category LC_CTYPE ), the result shall be the
corresponding uppercase letter. All other arguments in the domain are returned unchanged.
RETURN VALUE
Upon successful completion, toupper() shall return the uppercase letter corresponding to the argument
passed.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
setlocale() , the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 7, Locale, <ctype.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .