Compilare: user.cpp: In function ‘int main()’: user.cpp:14:16: 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:15:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘std::string* {aka std::basic_string<char>*}’ [-Wformat=] while (scanf("%s", &x) != EOF) ^ user.cpp:21:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = x.length(); i < s.size(); i++) ^ user.cpp:10:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.in", "r", stdin); ^ user.cpp:14:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", &s); ^