Compilare: main.cpp: In function 'void add(nod*, std::__cxx11::string&)': main.cpp:18:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.size(); i++){ ~^~~~~~~~~~~ main.cpp: In function 'bool if_all(nod*, std::__cxx11::string&)': main.cpp:29:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.size(); i++){ ~^~~~~~~~~~~ main.cpp: In function 'bool if_any(nod*, std::__cxx11::string&)': main.cpp:50:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.size(); i++){ ~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:75:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(c.size()<lmax){ ~~~~~~~~^~~~~