Library: Localization
Function
Locale convenience function that determines if a character is alphabetic
#include <locale> namespace std { template <class charT> bool isalpha(charT c, const locale& loc); }
The isalpha() function returns true if the character passed as a parameter is part of the alphabet specified by the locale parameter. Otherwise, the function returns false. The check is made using the ctype facet from the locale parameter.
ctype, locale, isalnum(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit()
ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 22.1.3.1