大数运算实现-优快云博客

// bigNumMultiplication.cpp : 定义控制台应用程序的入口点。
//
#pragma once;
#include "stdafx.h"
#include
#include
using namespace std;

class CBigNum
{
public:
CBigNum(){}
CBigNum(vector b):m_vData(b){}
CBigNum(size_t nValu)
{
  /*
   * 得到个位
   */
  size_t nGeWei = nValu % 10;
  m_vData.push_back(nGeWei);
  size_t nShanwei = (nValu-nGeWei)/10;
  while (nShanwei >= 10)
  {
   nGeWei = nShanwei%10;
   m_vData.push_back(nGeWei);
   nShanwei = (nShanwei-nGeWei)/10;
  }
  m_vData.push_back(nShanwei);
}
private:
vector m_vData;
public:
/*
* 重载减号
*/
friend CBigNum operator-(CBigNum &obj1,CBigNum &obj2)
{

  if(obj2.m_vData.size() > obj1.m_vData.size())
  {
   return obj2 - obj1;
  }
  CBigNum bj = obj1;
  vector::iterator it1 = obj.m_vData.begin();
  vector::iterator it2 = obj2.m_vData.begin();
  while (it1!=obj.m_vData.end() && it2 != obj2.m_vData.end())
  {
   calculateDecrease(it1,it2,obj.m_vData.end(),obj2.m_vData.end());
   it1++;
   it2++;
  }
  return obj;
}
friend ostream &operator< {
  vector::const_reverse_iterator it = obj.m_vData.rbegin();
  /*
   * 去掉末尾多的零
   */
  while (*it == 0)
  {
   it++;
  }
  while (it !=obj.m_vData.rend())
  {
   os<   it++;
  }
  return os;
}
/*
* 定义为friend 则需要两个参数
*/
friend CBigNum operator *(CBigNum &obj1,CBigNum &obj2)
{

  vector vTmp1 = obj1.m_vData;
  vector vTmp2 = obj2.m_vData;
  vector vTmp(vTmp1.size()+vTmp2.size(),0);
  for (size_t st1=0;st1  {
   for (size_t st2=0; st2 < vTmp2.size();++st2)
   {
    vTmp[st1+st2] += vTmp1[st1]*vTmp2[st2];
   }
  }
  calculateMultiplication(vTmp.begin(),vTmp.end());
  return CBigNum(vTmp);
}
private:
/*
* multiplication operator
*/
static void calculateMultiplication(vector::iterator itBeg,vector::iterator itEnd)
{
  if (itBeg == itEnd)
  {
   return;
  }
  size_t nTmp=*itBeg;
  if (nTmp >= 10)
  {
   size_t nTmp1=nTmp % 10;
   *(itBeg++) =nTmp1;
   *itBeg += (nTmp-nTmp1)/10;
  }
  else
  {
   itBeg++;
  }
  calculateMultiplication(itBeg,itEnd);
}
/*
* decrease operator
*/
static void calculateDecrease(vector::iterator &item1,vector::iterator &item2,
          vector::iterator &item1end,vector::iterator &item2end)
{
   if (*item1   {
    borrowOne(item1,item1end);
   }
   *item1=*item1 - *item2;
}
/*
* 借一作十
*/
static void borrowOne(vector::iterator itemBeg,vector::iterator itemEnd)
{
  /*
   * 不能借下
   */
  while (itemBeg == itemEnd)
  {
   return;
  }
  if (*(itemBeg+1)==0)
  {
   borrowOne(itemBeg+1,itemEnd);
  }
  *itemBeg += 10;
  *(itemBeg+1) -= 1;
}
};

int _tmain(int argc, _TCHAR* argv[])
{
//cout< vector v1;
//v1.push_back(7);
v1.push_back(1);
v1.push_back(1);
v1.push_back(1);
v1.push_back(1);
v1.push_back(1);
vector v2;
v2.push_back(1);
v2.push_back(1);
v2.push_back(1);
v2.push_back(1);
v2.push_back(1);
//v2.push_back(5);
//CBigNum b1(v1);
//CBigNum b2=b1;
//cout<