isblank
int isblank(int);
#ifdef isblank
#define ISBLANK(c) (isascii (c) && isblank (c))
BUILD_CHARCLASS_LOOP (isblank);
#if !defined _LIBC && ! (defined isblank || (HAVE_ISBLANK && HAVE_DECL_ISBLANK))
if (isblank(i))