rb_isdigit        925 complex.c          if (!rb_isdigit(RSTRING_PTR(s)[RSTRING_LEN(s) - 1]))
rb_isdigit       1181 include/ruby/ruby.h int rb_isdigit(int c);
rb_isdigit       1201 include/ruby/ruby.h #define ISDIGIT(c) rb_isdigit((unsigned char)(c))
rb_isdigit       1354 rational.c     		if (rb_isdigit(*p))