[Main]
Name=isextalnum
Type=Function
Subtype=Macro
Header Files=ctype.h
Definition=short isextalnum (short c);
Real Definition=#define isextalnum(c) ({register short __c=(c); (unsigned short)__c<256&&_extalnum_list[__c>>3]&(1<<(__c&7));})

[Description]
Checks whether a character is an extended alphanumeric.

[Explanation]
isextalnum returns nonzero if <I>c</I> is a symbol which may be used in variable names,
including ordinary alphanumerics (see <A HREF="$$LINK(ctype.h/isalnum)">isalnum</A>), underscore ('_') and
foreign alphanumerics (see <A HREF="$$LINK(ctype.h/isfrgnalnum)">isfrgnalnum</A>), otherwise it returns zero.
It is an inline function which is implemented using GNU C smart macros and a library variable. The first call of isextalnum
expands to a large code, but any next call of it expands to a relatively small code.
