Compilare: main.cpp: In function 'int main()': main.cpp:30:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | for (i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp:50:27: 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 (i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp:62:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 62 | for (i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp:71:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 71 | if (i == s.size()) fout << t->fr << "\n"; | ~~^~~~~~~~~~~ main.cpp:76:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 76 | for (i = 0; i < s.size(); i++) | ~~^~~~~~~~~~