EX3_vector

//Trong bai nay ta gia su nhan, cong cac vector co cung so cheu
//Vi thay giao noi nhu vay!!!!!!!hehe
//Con neu de xet cac vec to khac chieu thi phuc tap hon the nay!!!!xet sau!!hehe
#include<iostream>
using namespace std;
class vector
{
    private:
    int n;
    double *v;
    public:
    vector()
    {
        n=0;
    }
    vector(int n1)
    {
        n=n1;
        v=new double[n];
        for(int i=0;i<n;i++)
            v[i]=0;
    }
    ~vector()
    {
        delete [] v;
    }
    vector multiply(double x)
    {
        vector u(n);
        for(int i=0;i<n;i++)
            u.v[i]=(v[i])*x;
        return u;
    }
    double multiply(vector &u)
    {
        double multip=0;
        for(int i=0;i<n;i++)
            multip+=(v[i])*u.v[i];
        return multip;
    }
    void add(vector &u)
    {
        for(int i=0;i<n;i++)
            v[i]+=u.v[i];
    }
    void copyv(vector &u)
    {
        for(int i=0;i<n;i++)
            v[i]=u.v[i];
    }
    void reset(int n1)
    {
        n=n1;
        for(int i=0;i<n;i++)
            v[i]=0;
    }
    void input()
    {
        for(int i=0;i<n;i++)
        {
            double a;
            cin>>a;
            v[i]=a;
        }
    }
    void display()
    {
        for(int i=0;i<n;i++)
            cout<<(v[i])<<endl;

    }
};
int main()
{
    cout<<"Input the dimension of vector:"<<endl;
    int nx;
    cin>>nx;
    vector x(nx),y(nx);
    cout<<"Input the component of x:"<<endl;
    x.input();
    cout<<"Input the component of y:"<<endl;
    y.input();
    cout<<"Input one real number:"<<endl;
    double re;
    cin>>re;
    cout<<"x*re"<<endl;
    (x.multiply(re)).display();
    double mult;
    mult=x.multiply(y);
    cout<<"x*y="<<mult<<endl;
    vector z1(nx);
    z1.copyv(x);
    cout<<"z1=x"<<endl;
    z1.display();
    cout<<"x+y="<<endl;
    x.add(y);
    x.display();
    cout<<"Input n1 is new dimension to reset x:"<<endl;
    cin>>nx;
    x.reset(nx);
    cout<<"x after reset:"<<endl;
    x.display();
    return 0;
}