Compilare: main.cpp: In function 'int getnr(std::__cxx11::string)': main.cpp:28:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp: In function 'void parseExp(std::__cxx11::string)': main.cpp:45:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size()) ~~^~~~~~~~~~ main.cpp: In function 'int Exp(std::__cxx11::string)': main.cpp:69:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size() - 1) ~~^~~~~~~~~~~~~~ main.cpp: At global scope: main.cpp:161:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main() ^