polynomial operator+ function is causing the wrong output or is it print function - oop

Question

this is the output showing :
+2x^0 +0x^1 +0x^2 +0x^3 -5x^4
+0x^0 +0x^1 +0x^2 +0x^3 +6x^4 +0x^5 +0x^6 +0x^7 -9x^8
+2x^0 +0x^1 +0x^2 +0x^3 +1x^4 +0x^5 +0x^6 +0x^7 [phone]x^8 // output of p1+p2
why is is showing 158.... in x power 8 term .
it should show simply -9x^8 only .
i am trying to learn to implement operator overloading in it .
i think the problem is in loop of overloading function .
#include <iostream>
using namespace std ;
class polynomial {
int* degree ;
int capacity ;
public:
polynomial () {
degree = new int[5];
for ( int i = 0 ; i < 5 ; i ++){
degree[i] = 0 ;
}
capacity = 5 ;
}
// copy constructor
polynomial (const polynomial& p){
this -> degree = new int[p.capacity];
for( int i = 0 ; i < p.capacity ; i++){
this -> degree[i] = degree[i];
}
this -> capacity = p.capacity;
}
// assignment operator overload
void operator=(polynomial const &p){
this -> degree = new int[p.capacity];
for( int i = 0 ; i < p.capacity ; i++){
this -> degree[i] = p.degree[i];
}
this -> capacity = p.capacity;
}
void print(){
for ( int i = 0 ; i < capacity ; i ++ ){
if( degree[i] >= 0)
cout << "+"<< degree[i] <<"x^" <<i<<" ";
else cout<< degree[i] <<"x^" <<i << " ";
}
cout << endl;
}
void setCoefficient( int de , int num ){
if( de < capacity ){
degree[de] = num ;
}
else {
int ic = capacity ;
capacity = capacity+(de-capacity+1) ;
int* ne = new int[capacity];
for( int i = 0 ; i < capacity ; i ++){
ne[i] = 0 ;
}
for( int i = 0 ; i < ic; i ++){
ne[i] = degree[i];
}
delete [] degree;
degree = ne;
degree[de] = num ;
}
}
polynomial operator+( polynomial const &p){
polynomial tp ;
tp.capacity = max(capacity, p.capacity) ;
int i = 0 ;
for(; i < max(this->capacity, p.capacity) ; i ++){
if(i <= capacity && i <= p.capacity)
{tp.degree[i] = degree[i] + p.degree[i];}
else if ( i < p.capacity) tp.degree[i] = p.degree[i] ;
else tp.degree[i] = degree[i];
}
return tp;
}
polynomial operator-( polynomial const &p){
polynomial tp ;
tp.capacity = max(capacity, p.capacity) ;
for( int i = 0 ; i < max(this->capacity, p.capacity) ; i ++){
tp.degree[i] = degree[i] - p.degree[i];
}
return tp;
}
};
#include <bits/stdc++.h>
#include "polynomialClass.cpp"
using namespace std;
int main (){
polynomial p1 , p2 ;
p1.setCoefficient(4, -5);
p1.setCoefficient(0,+2);
p1.print();
p2.setCoefficient(8,-9);
p2.setCoefficient(4,+6);
p2.print();
polynomial p3 = p1 + p2;
p3.print();
}