CODEWITHSUNDEEP
c++shared-ptr
Kapil Sharma
Kapil Sharma

Reputation: 1432

shared_ptr with map (error error C2664)

I have a class with a shared_ptr data member. Below is an example

class A {
private:
    shared_ptr<map<int, std::string>> _pMap;
    A();
public:
    A(shared_ptr<map<int, std::string>>); 
    A(const A& source);
    A& operator=A(const A&);
};

A::A(shared_ptr<map<int, std::string>> mapPtr) 
: _pMap(new std::shared_ptr<std::map<int, std::string>>()) {
    _pMap = mapPtr;

A::A(const A& source) : _pMap(source._p) {}

A& A::operator=(const A& source) {
    if (this == &source) {
        return *this;
    }

    _pMap = source._pMap;

    return *this;
}

When I tried to compile my program with just the header included in the main program, I receive the following error: 

error C2664: 'std::_Ptr_base<_Ty>::_Reset0' : 
             cannot convert parameter 1 from 'std::shared_ptr<_Ty> *' 
             to 'std::map<_Kty,_Ty> *

But I am not sure where I am doing this. Can please someone guide as to why this might be happening?

Thanks.

Upvotes: 0

Views: 1057

Answers (2)

tsragravorogh
tsragravorogh

Reputation: 3153

I fixed part of your code:

class A 
{
private:
    shared_ptr<map<int, std::string>> _pMap;
    A();
public:
    A(shared_ptr<map<int, std::string>>);
    A(const A& source);
};

A::A(shared_ptr<map<int, std::string>> mapPtr)
{
    _pMap = mapPtr;
}

int main()
{
    shared_ptr<map<int, std::string>> myMap = std::make_shared<map<int, std::string>>
    ();
    A a(myMap);
    return 0;
}

Upvotes: 0

Wojtek Surowka
Wojtek Surowka

Reputation: 20993

The problem (or at least one of) is in the line

A::A(shared_ptr<map<int, std::string>> mapPtr) : _pMap(new std::shared_ptr<std::map<int, std::string>>()) {
        _pMap = mapPtr;

it should be

A::A(shared_ptr<map<int, std::string>> mapPtr) : _pMap(new std::map<int, std::string>()) {
        _pMap = mapPtr;

But there is not point to initialise _pMap twice - so for this constructor the best would be to do

A::A(shared_ptr<map<int, std::string>> mapPtr) : _pMap(mapPtr) { }

Upvotes: 4

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