extern int strcmp(const char *a2, const char *a1);
extern int strncmp(const char *a2, const char *a1, int n);
extern int strlen(const char *c);
+extern void strcat(char *dest, char *src);
extern void strcpy(char *a2, const char *a1);
extern void puts(const char *c);
extern void tohex(char *s, unsigned long l);