大家看看我这个大数相乘有什么问题，主要是函数返回处有问题。

#pragma once

#include <iostream>

using namespace std;

class BigNum1

{

public:

	BigNum1(void);

	~BigNum1();

	BigNum1(int *, int);

	BigNum1(BigNum1&);

	BigNum1& operator=(BigNum1 BigOne);

	BigNum1&  operator*(BigNum1 &bigOne);

	BigNum1& operator+(BigNum1 &bigOne);

	friend ostream&  operator<<(ostream &os, BigNum1 &BigOne);

private:

	long nlen;

	int *pData;

};





BigNum1::BigNum1(void)

{

	nlen = 0;

	pData = NULL;

}



BigNum1::~BigNum1(void)

{

	if (nlen != 0)

	{

		nlen = 0;

		delete[] pData;

		pData = NULL;

	}

}



BigNum1::BigNum1(int *data, int len)

{

	nlen = len;

	pData = new int[nlen];

	memcpy(pData, data, 4 * len);

}



BigNum1::BigNum1(BigNum1& BigOne) 

{

	if (this == &BigOne )

	{

		return;

	}

	nlen = BigOne.nlen;

	if (pData)

	{

		delete[] pData;

		pData = NULL;

	}

	pData = new int[nlen];

	memcpy(pData, BigOne.pData, nlen * 4);

}



BigNum1& BigNum1::operator=(BigNum1 bigOne)

{

	if (this == &bigOne)

	{

		return *this;

	}



	if (pData)

	{

		delete [] pData;

		pData = NULL;

	}

	nlen = bigOne.nlen;

	pData = new int[nlen];

	for (int i = 0; i < nlen; i++)

	{

		pData[i] = bigOne.pData[i];

	}

	return (*this);

}



BigNum1& BigNum1::operator+(BigNum1 &bigOne)

{

	long Maxlen = nlen > bigOne.nlen?nlen + 1: bigOne.nlen + 1;

	BigNum1 bigSum;

	bigSum.nlen = Maxlen;

	bigSum.pData = new int[Maxlen];

	memset(bigSum.pData, 0, 4 * Maxlen);

	int k = 0;

	for (int i = 0 ; i < Maxlen; i++)

	{

		int a, b;

		a = 0; 

		b = 0;

		if (i < nlen)

		{

			a = pData[i];

		}

		if (i < bigOne.nlen)

		{

			b = bigOne.pData[i];

		}

		int sum = a+ b + k;

		k = sum / 10;

		bigSum.pData[i] = sum %10;

	}

	return bigSum;

}



BigNum1& BigNum1::operator*(BigNum1& bigOne)

{

	BigNum1 IData;

	long maxLen = nlen + bigOne.nlen;

	IData.nlen = maxLen;

	IData.pData = new int[maxLen];

	memset(IData.pData, 0, IData.nlen * 4);

	for (int i = 0; i < nlen; i++)

	{

		BigNum1 Jdata;

		Jdata.nlen = maxLen;

		Jdata.pData = new int[maxLen];

		memset(Jdata.pData, 0, Jdata.nlen * 4);

		int a = 0;

		int b = 0;

		for (int j = 0; j < bigOne.nlen; j++)

		{

			int sum = pData[i] * bigOne.pData[j];

			sum += a;

			a = sum/ 10;

			b = sum % 10;

			Jdata.pData[i+j] = b;

		}

	/*	if (a != 0)

		{

			Jdata.pData[i + bigOne.nlen] = a;

		}*/

		IData = IData + Jdata;

	}

	cout<<IData;

	return IData;

}



ostream& operator<<(ostream& os, BigNum1 &bigOne)

{

	for ( int i = bigOne.nlen - 1; i >= 0; i--)

	{

		os<<bigOne.pData[i];

	}

	return os;

}



#include "stdafx.h"

#include "BigNum1.h"



int _tmain(int argc, _TCHAR* argv[])

{

	int np[] = {1,1};

	int nq[] = {2,1};

	//BigNum1 one(np, 2);

	BigNum1 two(nq, 2);

	two = two * two;

	cout<<two<<endl;

	return 0;

}

多谢了。