... English alphabet by default, any national characters, such as accentuated charac-ters in other languages, must be dealt with individually. A program of this type is knownas a filter and can be applied ... <<';'<<(c)<<'H')STANDARD MACROS FOR CHARACTER MANIPULATION■ 129 The following section introduces macros that classify or convert single characters. Themacros are defined in the header files ... , are available for classifying charac-ters. For example, the macro islower(c) checks whether c contains a lowercase letterreturning the value true, in this case, and false in all other cases.Example:...