c++ - Pointer or local variable for the output parameter of a function -

if want use value of element in map output parameter of function, better declare smart pointer or locally?

for example:

// .h class {    private:     // below code preferred on      // std::map<int, std::unique_ptr<b>>?     std::map<int, b> map;    public:     void func1();     // message output parameter     void func2(int, b* message); }   // .cc void a:: func1() {    b b;    // better make b smart pointer , use std::move     // transfer ownership map?    map.insert(std::make_pair(1, b));    (const auto& x : map) {      func2(x->first, &x->second);    } } 

in example above, better declare smart pointer b , pass pointer func2 instead?

thanks,

std::map makes copies of put in it¹, map owns copy of b provided func2. there no need smart pointers here map handle destruction of stored bs.

in fact there no need pointers @ all. func2 void func2(int, b & message); , use reference.

¹ can store pointer in std::map, , std::map contain copy of pointer. data pointed @ not copied , needs external management handle destruction. case using smart pointer, storing pointers in container defeats many of benefits of using container in first place , best avoided.