Compilare: main.cpp: In function 'bool evaluate_postfix(std::__cxx11::string)': main.cpp:165:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<postfix.length();i++){ ~^~~~~~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:218:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<c.length();i++){ ~^~~~~~~~~~~ main.cpp: In function 'bool apply(char, bool, bool)': main.cpp:51:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.cpp: In function 'bool get_value(char)': main.cpp:76:1: warning: control reaches end of non-void function [-Wreturn-type] } ^