Error while implementing smart pointer class

Question

I am stuck at a single error. Here is my code:

 template<class t>
 class smart_ptr{
    t *ptr;
 public: 
    smart_ptr(t *p):ptr(p){cout<<"smart pointer copy constructor is called"<<endl;} 

    ~smart_ptr(){cout<<"smart pointer destructor is called"<<endl;delete(ptr);}
    t& operator *(){cout<<"returning the * of pointer"<<endl;return(*ptr);}
    t* operator ->(){cout<<"returning the -> of pointer"<<endl;return(ptr);}
    t* operator=(const t &lhs){ptr=lhs;cout<<"assignement operator called"<<endl;}
   };
   class xxx{
            int x;
    public:
            xxx(int y=0):x(y){cout<<"xxx constructor called"<<endl;}
            ~xxx(){cout<<"xxx destructor is called"<<endl;}
            void show(){cout<<"the value of x="<<x<<endl;}
    };
 int main(int argc, char *argv[])
 {
    xxx *x1=new xxx(50);
    smart_ptr<xxx *> p1(x1);
    return 0;
 }

While compilation I am getting below error

smart_pointer_impl.cpp: In function ‘int main(int, char**)’:

smart_pointer_impl.cpp:27: error: no matching function for call to ‘smart_ptr::smart_ptr(xxx*&)’

smart_pointer_impl.cpp:7: note: candidates are: smart_ptr::smart_ptr(t*) [with t = xxx*]

smart_pointer_impl.cpp:4: note: smart_ptr::smart_ptr(const smart_ptr&)

Any help for a solution is most welcome.

Dario Digiuni · Accepted Answer · 2013-11-05 15:37:34Z

2

Presumably smart_ptr is template<class t> and then in the main there was intended to be smart_ptr<xxx> instead of smart_ptr<xxx*>?

answered Nov 5, 2013 at 15:37

Dario Digiuni

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Comments

Grimm The Opiner · Accepted Answer · 2013-11-06 10:50:34Z

0

You need to change ::

smart_ptr<xxx *> p1(x1); to smart_ptr<xxx> p1(x1);

it will work.

edited Nov 6, 2013 at 10:50

Grimm The Opiner

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answered Nov 5, 2013 at 15:54

Santosh Sahu

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Comments

Grimm The Opiner · Accepted Answer · 2013-11-05 15:42:41Z

0

You have, I hope, forgotten the first line of your code, that being

 template<class t>

and this line:

smart_ptr<xxx *> p1(x1);

should be:

smart_ptr<xxx> p1(x1);

answered Nov 5, 2013 at 15:42

Grimm The Opiner

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Comments

Component 10 · Accepted Answer · 2013-11-05 15:43:36Z

0

You've not declared your class smart_ptr as a template

template <TYPE>
class smart_ptr{
    TYPE *ptr;
public: 
    smart_ptr(TYPE *p):ptr(p){cout<<"smart pointer copy constructor is called"<<endl;} 

    ~smart_ptr(){cout<<"smart pointer destructor is called"<<endl;delete(ptr);}
    TYPE& operator *(){cout<<"returning the * of pointer"<<endl;return(*ptr);}
    TYPE* operator ->(){cout<<"returning the -> of pointer"<<endl;return(ptr);}
    TYPE* operator=(const TYPE &lhs){ptr=lhs;cout<<"assignement operator called"<<endl;}
};

Also, you're declaring your pointer as of type 'pointer to xxx' but your template class is of a pointer to the type. Try:

smart_ptr<xxx> p1(x1);

edited Nov 5, 2013 at 15:43

answered Nov 5, 2013 at 15:37

Component 10

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