#include <iostream>#include <string>#include <typeinfo> struct Base{};// non-polymorphicstruct Derived: Base{}; struct Base2{virtualvoid foo(){}};// polymorphicstruct Derived2: Base2{}; int main(){int myint=50;std::string mystr="string";double*mydoubleptr= nullptr; std::cout<<"myint has type: "<<typeid(myint).name()<<'\n'<<"mystr has type: "<<typeid(mystr).name()<<'\n'<<"mydoubleptr has type: "<<typeid(mydoubleptr).name()<<'\n'; // std::cout << myint is a glvalue expression of polymorphic type; it is evaluatedconststd::type_info& r1=typeid(std::cout<< myint);// side-effect: prints 50std::cout<<'\n'<<"std::cout<<myint has type : "<< r1.name()<<'\n'; // std::printf() is not a glvalue expression of polymorphic type; NOT evaluatedconststd::type_info& r2=typeid(std::printf("%d\n", myint));std::cout<<"printf(\"%d\\n\",myint) has type : "<< r2.name()<<'\n'; // Non-polymorphic lvalue is a static type    Derived d1;    Base& b1= d1;std::cout<<"reference to non-polymorphic base: "<<typeid(b1).name()<<'\n';     Derived2 d2;    Base2& b2= d2;std::cout<<"reference to polymorphic base: "<<typeid(b2).name()<<'\n'; try{// dereferencing a null pointer: okay for a non-polymorphic expressionstd::cout<<"mydoubleptr points to "<<typeid(*mydoubleptr).name()<<'\n';// dereferencing a null pointer: not okay for a polymorphic lvalue        Derived2* bad_ptr= nullptr;std::cout<<"bad_ptr points to... ";std::cout<<typeid(*bad_ptr).name()<<'\n';}catch(conststd::bad_typeid& e){std::cout<<" caught "<< e.what()<<'\n';}}

======== output from Clang ========myint has type: imystr has type: NSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEEmydoubleptr has type: Pd50std::cout<<myint has type : NSt3__113basic_ostreamIcNS_11char_traitsIcEEEEprintf("%d\n",myint) has type : ireference to non-polymorphic base: 4Basereference to polymorphic base: 8Derived2mydoubleptr points to dbad_ptr points to...  caught std::bad_typeid ======== output from MSVC ========myint has type: intmystr has type: class std::basic_string<char,struct std::char_traits<char>,⮠class std::allocator<char> >mydoubleptr has type: double * __ptr6450std::cout<<myint has type : class std::basic_ostream<char,struct std::char_traits<char> >printf("%d\n",myint) has type : intreference to non-polymorphic base: struct Basereference to polymorphic base: struct Derived2mydoubleptr points to doublebad_ptr points to...  caught Attempted a typeid of nullptr pointer!