extern char *strcpy(char *dest, const char *src);
extern char *strncpy(char *dest, const char *src, size_t n);
extern char *strcat(char *dest, const char *src);
+extern char *strchr(const char *s, int c);
extern int strcmp(const char *s1, const char *s2);
+extern int strncmp(const char *s1, const char *s2, size_t n);
extern size_t strlen(const char *s);
extern size_t strnlen(const char *s, size_t count);