Compilare: main.cpp: In function 'int f(std::string)': main.cpp:33:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | for(int i=0;i<s.size();i++) | ~^~~~~~~~~ main.cpp:38:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | while(i<s.size()&&'0'<=s[i]&&s[i]<='9') | ~^~~~~~~~~ main.cpp: In function 'int calc(int, int, int)': main.cpp:27:1: warning: control reaches end of non-void function [-Wreturn-type] 27 | } | ^