isfrgn Function (Macro)

ctype.h

short isfrgn (short c);

Checks whether a character is a foreign letter.

isfrgn returns nonzero if c is a foreign letter (including Greek ones), either uppercase or lowercase (see isGreek, isfrgnupper and isfrgnlower), otherwise it returns zero. It is an inline function which is implemented using GNU C smart macros, which expands to a relatively large code.