Description

The isupper() function tests for any character that is an uppercase letter or is one of an implementation-defined set of characters for which none of programming c:function iscntrl, programming c:function isdigit, programming c:function ispunct, or programming c:function isspace is true. In the C locale, isupper() returns true only for the characters defined as uppercase letters.

The behavior of the isupper() function is affected by the current locale. To modify the behavior, change the LC_CTYPE category in setlocale(), that is, setlocale(LC_CTYPE, newlocale). In the C locale or in a locale where character type information is not defined, characters are classified according to the rules of the U.S. ASCII 7-bit coded character set.

Parameters

• c Is an integer whose value is representable as an unsigned char, or the value of the macro EOF.

Return Values

The isupper() function returns non-zero for true and zero for false. If the parameter is not in the domain of the function, the return result is undefined.