Stuck in this need help

[herold]

Hi,
I am stuck in the following code.I'm beginner in C++. I am facing problem in the following code.if any one from you help me it will be very helpful to me.

#include<iostream>

using namespace std;

class vector
{
int *v;
int size;
public:
vector(int m)
{
cout<<"In the constructor of vector which takes argument of int"<<endl;
v=new int[size=m];
cout<<"Declared array of size and pointed to pointer v"<<endl;
for(int i=0;i<size;i++)
{

v[i]=0;
cout<<"Assigned v["<<i<<"]=0"<<endl;
}
}
vector(int *a)
{
cout<<&size<<endl;
cout<<"Size:"<<size<<endl;
/* for(int i=0;i<size;i++)
{
//v[i]=a[i];

}
*/
}
int operator *(vector &y)
{
cout<<"In operator function"<<endl;
int sum=0;
for(int i=0;i<size;i++)
{
sum +=this->v[i] * y.v[i];

}

return sum;
}
};
int main()
{
int x[]={5,6,7};
int y[]={7,8,9};

vector v1(3);
vector v2(3);


v1=x;
v2=y;



int r=v1*v2;
cout<<"Calling the * operator function"<<endl;
cout<<"The value of r:"<<r<<endl;


return 0;
}

Problem is in size variable.I'm assigning value size to 3 in first constructor but at when it calls second constructor which takes array pointer as argument value of size is changed despite calling from same object. Kindly help.Need help.

[vlad from moscow]

I do not see where the second constructor is called. Your code shall not be compiled because class vector has no an assignment operator that has a parameter of type int *.

[coder777]

yes, the second constructor is called here:

v1=x;
v2=y;

A constructor is only called for a newly created object. After the assignment of v1/v2 they are not the object created above.

Test it with cout << this

[vlad from moscow]

Ah, I am sorry. As there is the conversion constructor then in the right side of the expression

v1 = x;

constructor vector( int * ) is called. As it initializes neither v nor size then vector v1 gets these undefined values due to the default copy assignment operator.

[herold]

Thank you to "vlad". This program is in my text book.I was worried because i have never seen where text book is wrong. Problem is solved by removing the first constructor.
I assigned

v

in this constructor which was previously assigned in first constructor .

vector (T* a)
{
    v=new T[size];

    for(int i=0;i<size;i++)
    v[i]=a[i];
}

and now in my main function

Instead of declaring this

vector <int> v1;
vector <int>v2;

i declared in following manner.

vector <int> v1=x;
vector <int>v2=y;

And yes Size is constant here which is

3