Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #70246

I'm not able to find the error

Show all headers | View raw

Hello guys,
I've written this code to get acquainted to assignment operators,
move constructors and move assignment operators, but I got a
strange behavior in my code:
I report it in its fullness because it's 123 lines:

// code starts here
#include <iostream>

using std::cout;
using std::ostream;

class Vector
{
     friend ostream& operator<<(ostream& os, Vector& v)
     {
         for(size_t i=0; i<v.size(); i++)
             os << v[i] << ' ';

         return os << '\n';
     }

     public:
     Vector(int n=5) : sz(n), data( new int[n])
     {
         for(size_t i=0; i < sz; i++)
         data[i] = 0;
     }

     Vector(const Vector& r) :              // the copy constructor
         sz(r.size()),
         data( new int[sz] )
     {
         for(size_t i=0; i < sz; i++)
             data[i] = r.data[i];
     }


     Vector(const Vector&& r)               // the move constructor
             sz{r.size()},
             data{r.data}
     { }

     Vector& operator= (const Vector& r)    // the copy assignment
     {
         delete [] data;

         sz = r.size();
         data = new int[sz];

         for(size_t i=0; i < sz; i++)
             data[i] =  r.data[i];

         return *this;
     }

     Vector& operator= (const Vector&& r)    // the move assignment
     {
         delete [] data;

         data = new int[r.size()];
         data = r.data;

         return *this;
     }

     ~Vector()                                 // the destructor
     {
         cout << "deleting memory of array ";
         cout << *this;

         delete [] data;
         data = nullptr;
     }

     unsigned int size() const { return sz; }

     int& operator[] (int i) { return data[i]; }

     Vector operator+(Vector& rhs)
     {
         size_t maxdim = sz, mindim = sz;

         if(sz < rhs.size())
         {
             maxdim = rhs.size();
         }
         else
         {
             mindim = rhs.size();
         }

         Vector temp (maxdim);

         for(size_t i=0; i < mindim; i++)
             temp[i] = data[i] + rhs[i];

         return temp;
     }

     private:
     size_t  sz;
     int    *data;
};

int main()
{
     Vector v1(3), v2;

     cout << "v1.size() = " << v1.size() << '\n'
          << "v2.size() = " << v2.size() << "\n\n";

     v1[1] = 1; v2[2] = 3;   // using the index of '[]' operator

     cout << "v1 = " << v1;
     cout << "v2 = " << v2;


     Vector s;
     s = v1 + v2;         // these two lines give runtime error

//    Vector s = v1 + v2;     // this line is ok instead

     cout << "v1 + v2 = " << s << '\n';

     cout << "destroying objects..." << '\n';

     return 0;
}
// code ends here


Now I give a description of the error.
g++ executing this code on my gives:

v1.size() = 3
v2.size() = 5

v1 = 0 1 0
v2 = 0 0 3 0 0
deleting memory of array 0 1 3 0 0
v1 + v2 = 0 0 -1704935408 22058 0

destroying objects...
deleting memory of array 0 0 -1704935408 22058 0
free(): double free detected in tcache 2
aborted

As the title of the message says, I'm stuck.
I did my best to write it, but evidently some subtle error lays
between those lines.

If you comment the following:

     Vector s;
     s = v1 + v2;

and uncomment

//    Vector s = v1 + v2;

the program behaves correctly.
What could it be the problem?

Thank you.

Back to comp.lang.c++ | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-04 17:54 +0100
  Re: I'm not able to find the error Volker Wippel <Volker.Wippel@v2c2RemoveNoSpam.at> - 2019-12-04 18:40 +0100
  Re: I'm not able to find the error Daniel <danielaparker@gmail.com> - 2019-12-04 10:01 -0800
    Re: I'm not able to find the error Daniel <danielaparker@gmail.com> - 2019-12-04 10:06 -0800
  Re: I'm not able to find the error Manfred <noname@add.invalid> - 2019-12-04 20:16 +0100
    Re: I'm not able to find the error Manfred <invalid@add.invalid> - 2019-12-05 01:42 +0100
      Re: I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-05 03:45 +0100
        Re: I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-05 03:58 +0100
          Re: I'm not able to find the error Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2019-12-05 04:10 +0000
            Re: I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-05 05:45 +0100
          Re: I'm not able to find the error Manfred <noname@add.invalid> - 2019-12-05 17:29 +0100
  Re: I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-04 22:52 +0100
    Re: I'm not able to find the error Daniel <danielaparker@gmail.com> - 2019-12-04 16:47 -0800
      Re: I'm not able to find the error alexo <alelvb@inwind.it> - 2019-12-05 03:37 +0100

csiph-web