c++ - Determining the type from a smart pointer -

i have function takes in 2 template parameters. 1 expected smart pointer, , other expected object type. example, smartptr<myobject> first template parameter , myobject second template parameter.

template <typename t, typename tobject> 

i know whether can determine second parameter, myobject, automatically first parameter smartptr<myobject> or not template function written this:

template <typename t> 

and type tobject in original template function automatically determined t expected smart pointer.

as requested, here function declaration , use:

template <typename t, typename tobject> t* createormodifydoc(t* doc, myhashtable& table) {     t* ptr = null;      if (!table.findelement(doc->id, ptr))     {         table.addelement(doc->id, new tobject());         table.findelement(doc->id, ptr);     }             return ptr; } 

if know first template parameter smart pointer type, why not declare function 1 parameter , use such:

template<typename t> void whatisit(smartptr<t> ptr) {      printf("it a: %s" typeid(t).name()); }