char *strcat(char *dest, const char *src);
char *strncat(char *dest, const char *src, size_t len);
int strcmp(const char *s1, const char *s2);
char *strcat(char *dest, const char *src);
char *strncat(char *dest, const char *src, size_t len);
int strcmp(const char *s1, const char *s2);