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:46:10: 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:68:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size() - 1) ~~^~~~~~~~~~~~~~ main.cpp: In function 'int eval(std::__cxx11::string)': main.cpp:146:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp:155:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size() && s[i] >= '0' && s[i] <= '9') ~~^~~~~~~~~~ main.cpp:161:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i < s.size()) ~~^~~~~~~~~~ main.cpp: At global scope: main.cpp:227:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main() ^ main.cpp: In function 'int calc(char, int, int)': main.cpp:139:1: warning: control reaches end of non-void function [-Wreturn-type] } ^