NAME
isupper — test for
an uppercase letter
SYNOPSIS
#include
<ctype.h>
int isupper(int c);
DESCRIPTION
[CX] 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 IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.
The isupper () function shall
test whether c is a character of class
upper in the
program's current locale; see the Base Definitions volume of
IEEE Std 1003.1-2001 (“POSIX.1”),
xbd_chap07(7).
The c argument is an int, the value of which the application shall ensure is a character representable as an unsigned char or equal to the value of the macro EOF. If the argument has any other value, the behavior is undefined.
RETURN VALUE
The isupper () function shall return
non-zero if c is an uppercase letter; otherwise, it shall
return 0.
ERRORS
No errors are defined.
EXAMPLES
None.
APPLICATION USAGE
To ensure applications portability, especially across natural languages, only this function and those listed in the SEE ALSO section should be used for character classification.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
isalnum(3), isalpha(3), iscntrl(3), isdigit(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isxdigit(3), setlocale(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), xbd_chap07(7), <ctype.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 6
The DESCRIPTION is updated to avoid use of the term "must" for application requirements.
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