c++ - How to tell if a type is a subclass using type_info? -

i use c++ rtti. have type_info of class. how can tell whether class subclass of first one, if have type_info?

#include <typeinfo>  class foo             { public: virtual ~foo() {} }; class boo: public foo { public: virtual ~boo() {} }; class bar             { public: virtual ~bar() {} };  template<class t> bool instanceof(const type_info& info) {   // answer comes here!! }  int main(int argc, const char* argv[]) {   const type_info& fooinfo = typeid(foo);   const type_info& barinfo = typeid(bar);    bool booisfoo = instanceof<boo>(fooinfo); // should true   bool booisbar = instanceof<boo>(barinfo); // should false    return 0; } 

if have 2 typeinfo , b. there no general way determine if subclass of b.

you may:

1. store information (static structure filled @ runtime?)
2. make educated guesses using type name (i.e. parsing type info string , name types accordingly).

previous answers. require instantiate type somehow:

type_info not right tool this, should dynamic_cast if absolutely want check @ runtime:

template<class base, typename derived> bool instanceof(const derived& object) {   return !dynamic_cast<base*>(object); } 

you can check @ compile time using std::is_base_of steephen mentioned (c++11 needed).

template <typename base, typename derived> static constexpr bool instanceof() {     return std::is_base_of<base, derived>() } 

another solution:

template <typename base, typename derived> bool instanceof(const derived& object) {   try {       throw object;   } catch (const base&) {       return true;   } catch (...) {       return false;   } }