extern char *strchr(const char *str, int character);
extern char *strrchr(const char *str, int character);
extern char *strstr(const char *str1, const char *str2);
extern char *strchr(const char *str, int character);
extern char *strrchr(const char *str, int character);
extern char *strstr(const char *str1, const char *str2);