Compilare: main.cpp: In function 'void add(trie*, std::string&)': main.cpp:22:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 22 | for (int i=0; i<sir.size (); i++) | ~^~~~~~~~~~~~ main.cpp: In function 'void del(trie*, std::string&)': main.cpp:34:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for (int i=0; i<sir.size (); i++) | ~^~~~~~~~~~~~ main.cpp: In function 'int ap(trie*, std::string&)': main.cpp:50:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 50 | for (int i=0; i<sir.size (); i++) | ~^~~~~~~~~~~~ main.cpp: In function 'int pref(trie*, std::string&)': main.cpp:67:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 67 | for (int i=0; i<sir.size (); i++) | ~^~~~~~~~~~~~