Description

The isalpha() function tests for any character for which programming c:function isupper or programming c:function islower is true, or any character that 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 isspaceis true. In the C locale, isalpha() returns true only for the characters for which programming c:function isupper or programming c:function islower is true.

The behavior of the isalpha() 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 isalpha() 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.