Compilare: user.cpp: In function ‘int main()’: user.cpp:26:19: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘std::string* {aka std::basic_string<char>*}’ [-Wformat=] scanf("%s", &s); ^ user.cpp:29:24: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘std::string* {aka std::basic_string<char>*}’ [-Wformat=] printf("%s", &s); ^ user.cpp:23:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("carry.in", "r", stdin); ^ user.cpp:24:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("carry.out", "w", stdout); ^ user.cpp:25:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ user.cpp:26:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", &s); ^