decimal to binary conversion (c++)

#include<iostream>
using namespace std;
class A
{
 int x,n,k,a[2000],i,j;
 public:A(int o)
 {k=o;}
 void binary_equiv()
 {i=0;
 x=k;
 while(x!=1)
 {a[i]=x%2;
 x/=2;
 i+=1;}}
 void display()
 {
 int r=1;
 for(j=i-1;j>=0;j--)
 {
     r++;
 }
 n=8-r;

 cout<<"\nThe binary equivalent of "<<k<<" is :";
 j=1;
 while(j<=n)
{ cout<<"0";
  j+=1;}
  cout<<"1";
 for(j=i-1;j>=0;j--)
{cout<<a[j];}
}
};

int main()
{
 int num;
 cout<<"\nEnter the decimal number:";
 cin>>num;
 A obj(num);
 obj.binary_equiv();
 obj.display();
}