c++中如何完整输出两大数的和

#include<iostream>
#include<string>
#include<iomanip>
#include<algorithm>
using namespace std;
#define MAXN 9999
#define DLEN 4
class BigNum{
public:
int a[10000];//?????????
int len; //????
public:
BigNum(){len = 1;memset(a,0,sizeof(a));}
BigNum(const int);
BigNum(const char*);
BigNum(const BigNum &);
BigNum &operator=(const BigNum &);
//BigNum &operator>>
// friend ostream& operator>>(ostream&, BigNum&);
BigNum operator+(const BigNum &) const;
BigNum operator-(const BigNum &) const;
BigNum operator*(const BigNum &) const;
BigNum operator/(const int &) const;
BigNum operator^(const int &) const;
int operator%(const int &) const;
bool operator>(const BigNum & T)const;
void print();
};
// ostream& operator>>(ostream&os, BigNum &b)
// {
// char ch;
// int i