#define _U 01 #define _L 02 #define _A 03 #define _N 04 #define _S 010 extern char _ctype[]; #define isalpha(c) (_ctype[c]&_A) #define isupper(c) (_ctype[c]&_U) #define islower(c) (_ctype[c]&_L) #define isdigit(c) (_ctype[c]&_N) #define isspace(c) (_ctype[c]&_S) #define toupper(c) ((c)-'a'+'A') #define tolower(c) ((c)-'A'+'a')