HelenOS sources

isdigit            37 boot/generic/include/macros.h #define isdigit(d)  (((d) >= '0') && ((d) <= '9'))
isdigit            52 common/stdc/ctype.c int isdigit(int c)
isdigit            52 kernel/generic/common/stdc/ctype.c int isdigit(int c)
isdigit           104 kernel/generic/include/macros.h #define isdigit(d)     (((d) >= '0') && ((d) <= '9'))
isdigit            52 uspace/lib/c/common/stdc/ctype.c int isdigit(int c)
isdigit            97 uspace/lib/cpp/include/__bits/locale/locale_misc.hpp     bool isdigit(Char c, const locale& loc)