c++ - How to correct the overloading assignment in this program? -

hello everyone: struggling assign cof of 1 class object class object. however, why overloading(=) can assign first 2 cofs!(cof pointer int)

i new here, not sure how enter mu code here. hope can me! thanks! code:

#include <iostream> using namespace std; class polynomial { private :      int* cof;      int size;   public :   polynomial();   polynomial(int );   polynomial(const polynomial& a);   ~polynomial();   int getvalue() const;   void operator =(const polynomial& a);    void output(const polynomial& p); };     int main() {    int m;     cout<<"how many numbers in p1 :"<<endl;     cin>>m;     polynomial p1(m);     cout<<"how many numbers in p2"<<endl;     cin>>m;     polynomial p2(m);     cout<<"the p1's cof"<<endl;     p1.output(p1);     cout<<"the p2's cof"<<endl;     p2.output(p2);     polynomial t;     t=p1;      cout<<" t's cof:"<<endl;     t.output(t);     t=p2;      cout<<"the t's cof:"<<endl;     t.output(t);     return 0; }      polynomial::~polynomial() { delete [] cof;} polynomial:: polynomial():size(1) {   cof= new int[size];     cof[0]=0; } polynomial::polynomial(int a): size(a) {  cof= new int[size+1];    cout<<"please enter numbers:"<<endl;    for(int i=0;i<size+1;i++)        cin>>cof[i];    } polynomial::polynomial(const polynomial& a)    {  cof= new int[a.size+1];       for(int i=0;i<=a.size;i++)       {   cof[i]=a.cof[i];}   }   int polynomial::getvalue() const {  return size;}     void polynomial::output(const polynomial& p) {  for(int i=0;i<=p.size;i++)     { cout<<p.cof[i]<<" ";}       cout<<endl; }       void polynomial::operator =(const polynomial& a)  {  if (cof!=null)         delete [] cof;     int x=a.getvalue();     cof= new int[x+1];     for(int i=0;i<=x;i++)     {  cof[i]=a.cof[i];}  } 

you forgot copy size.

void polynomial::operator =(const polynomial& a) {   if (cof!=null) delete [] cof;   size = a.getvalue();                               // <<< !!!   cof = new int[size+1];   for(int = 0; < size + 1; i++){     cof[i]=a.cof[i];}   } } 

coding easier if drop outdated c-style array , use std::vector instead. drop size (use vector's size) , copy vector.

also, calling getter (getvalue()) different member (size) apt cause confusion.