3.7 islower, islower_l—lowercase character predicate

Synopsis

     #include <ctype.h>
     int islower(int c);
     
     #include <ctype.h>
     int islower_l(int c, locale_t locale);
     

Description
islower is a macro which classifies singlebyte charset values by table lookup. It is a predicate returning non-zero for minuscules (lowercase alphabetic characters), and 0 for other characters. It is defined only if c is representable as an unsigned char or if c is EOF.

islower_l is like islower but performs the check based on the locale specified by the locale object locale. If locale is LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.

You can use a compiled subroutine instead of the macro definition by undefining the macro using `#undef islower' or `#undef islower_l'.

No supporting OS subroutines are required.