Compilare: main.cpp: In function 'int mult()': main.cpp:30:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | while(pos<s.size() && (s[pos]=='*' || s[pos]=='/')) | ~~~^~~~~~~~~ main.cpp: In function 'int add()': main.cpp:49:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 49 | while(pos<s.size() && (s[pos]=='+' || s[pos]=='-')) | ~~~^~~~~~~~~