大数运算器

该项目主要是对超过计算机计算范围的数字进行加减乘除运算,若被操作数都没超过计算机表示范围,且计算机都能进行相关运算,则调用计算机进行相关运算,若超过运算范围的,则调用下面相关函数就可以进行相关运算。

主要思想就是对超出存储范围的数字都以字符串的形式进行存储起来,然后模拟十进制的加减乘除运算。具体如何模拟运算则需要看下面的代码实现过程

代码如下:

头文件:BigData.h

#pragma once
#include<iostream>
#include<string>
#include<assert.h>
using namespace std;


typedef long long INT64;
#define MIN_INT64 0x8000000000000000
#define MAX_INT64 0x7FFFFFFFFFFFFFFF


class BigData
{
public:
	BigData(INT64 x);
	BigData(const char* cData);

	BigData operator+(const BigData& bigdata);
	BigData operator-(const BigData& bigdata);
	BigData operator*(const BigData& bigdata);
	BigData operator/(const BigData& bigdata);

protected:
	string Add(string left, string right);
	string Sub(string left, string right);
	string Mul(string left, string right);
	string Div(string left, string right);

	friend ostream& operator<<(ostream& out, const BigData& bigdata);
	bool isOverFlowINT64()const;
	bool IsLeftStrBig(const char* pLeft, int Lsize, const char* pRight, int Rsize);
	char subloop(char* pLeft, int Lsize, char* pRight, int Rsize);
	void _INIT64ToString();

private:
	INT64 _value;
	string _strData;
};
函数实现部分:BigData.cpp

#include"BigData.h"

BigData::BigData(INT64 x)
   :_value(x)
{
	_INIT64ToString();
}


BigData::BigData(const char* cData)
{
	if (cData == NULL)
	{
		assert(false);
		return;
	}

	char* ptr = (char*)cData;
	char cSymbol = cData[0];   //“0000”  ""

	if (cSymbol == '-' || cSymbol == '+')
	{
		ptr++;
	}
	else if (cSymbol >= '0' && cSymbol <= '9')
	{
		cSymbol = '+';
	}
	else
	{
		return;
	}

	while (*ptr == '0')
	{
		++ptr;
	}

	_strData.resize(strlen(cData) + 1);
	_strData[0] = cSymbol;

	_value = 0;
	int iCount = 1;

	while (*ptr >= '0' && *ptr <= '9')
	{
		_value = _value * 10 + (*ptr - '0');
		_strData[iCount++] = *ptr;
		++ptr;
	}

	_strData.resize(iCount);

	if (cSymbol == '-')
	{
		_value = 0 - _value;
	}
}

void BigData::_INIT64ToString()
{
	char cSymbol = '+';
	if (_value < 0)
	{
		cSymbol = '-';
		//----------------------------------------------------
	}

	INT64 tmp = _value;
	_strData.append(1, cSymbol);

	while (tmp)
	{
		_strData.append(1, tmp % 10 + '0');
		tmp /= 10;
	}

	char* pLeft = (char*)_strData.c_str() + 1;
	char* pRight = pLeft + _strData.size() - 2;

	while (pLeft < pRight)
	{
		char cmp = *pLeft;
		*pLeft = *pRight;
		*pRight = cmp;
		pLeft++;
		pRight--;
	}
}

bool BigData::isOverFlowINT64()const
{
	string tmp("9223372036854775807");

	if (_strData[0] == '-')
	{
		tmp = "-9223372036854775808";
	}

	if (_strData.size() < tmp.size())
	{
		return true;
	}
	else if (_strData.size() == tmp.size() && _strData<tmp)
	{
		return true;
	}

	return false;
}


ostream& operator<<(ostream& out, const BigData& bigdata)
{

	if (bigdata.isOverFlowINT64())
	{
		out << bigdata._value;
		return out;
	}
	else
	{
		char* pstr = (char*)bigdata._strData.c_str();

		if (pstr[0] == '+')
		{
			pstr++;
		}
		out << pstr;
	}
	return out;
}


BigData BigData::operator+(const BigData& bigdata)
{
	if (isOverFlowINT64() && bigdata.isOverFlowINT64())
	{
		if (_strData[0] != bigdata._strData[0])
		{
			return (_value + bigdata._value);
		}
		else
		{
			INT64 tmp = MIN_INT64;
			if (_value > 0 && MAX_INT64 - _value >= bigdata._value
				|| _value < 0 && tmp - _value <= bigdata._value)    //--------------
			{
				return (_value + bigdata._value);
			}
		}
	}

	if (_strData[0] == bigdata._strData[0])    //同号溢出的情况,调用加法------------------------------
	{
		return BigData(Add(_strData, bigdata._strData).c_str());   
	}

	return BigData(Sub(_strData, bigdata._strData).c_str()); //异号溢出的情况,调用减法
}

BigData BigData::operator-(const BigData& bigdata)
{
	if (isOverFlowINT64() && bigdata.isOverFlowINT64())
	{
		if (_strData[0] == bigdata._strData[0])    //同号相减肯定不会溢出
		{
			return BigData(_value - bigdata._value);
		}
		else
		{
			if ((_value > 0 && MAX_INT64 + bigdata._value >= _value) ||     //肯定不会溢出
				(_value < 0 && MIN_INT64 + bigdata._value <= _value))
			{
				return BigData(_value - bigdata._value);
			}
		}
	}

	if (_strData[0] != bigdata._strData[0])        //会溢出
	{
		return BigData(Add(_strData,bigdata._strData).c_str());
	}

	return BigData(Sub(_strData, bigdata._strData).c_str());
}

BigData BigData::operator*(const BigData& bigdata)
{
	if (_value == 0 || bigdata._value == 0)
	{
		return BigData(INT64(0));
	}
	if (isOverFlowINT64() && bigdata.isOverFlowINT64())
	{
		if (_strData[0] == bigdata._strData[0])
		{
			if ((_value > 0 && MAX_INT64 / _value >= bigdata._value) ||     //同号且不会溢出
				(_value < 0 && MIN_INT64 / _value <= bigdata._value))    //  -10 -2 = 5 
			{
				return BigData(_value * bigdata._value);
			}
		}
		else
		{
			//-10 2 -5                                                         //异号且不会溢出
			if ((_value > 0 && MIN_INT64 / _value <= bigdata._value) ||      //-10  2  = -5 <= -3 
				(_value < 0 && MIN_INT64 / _value >= bigdata._value))        //-10 -2  =  5  >= 3
			{
				return BigData(_value * bigdata._value);
			}
		}
	}

	return BigData(Mul(_strData, bigdata._strData).c_str());     //溢出调用Mul
}


BigData BigData::operator/(const BigData& bigdata)
{
	if (bigdata._strData[1] == '0')      //处理除数为0的情况
	{
		assert(false);
	}

	if (isOverFlowINT64() && bigdata.isOverFlowINT64())   //处理不溢出的情况
	{
		return BigData(_value / bigdata._value);
	}

	if (_strData.size() < bigdata._strData.size() ||    //左边小于右边的情况
		(_strData.size() == bigdata._strData.size()
		&& strcmp(_strData.c_str() + 1, bigdata._strData.c_str() + 1) < 0))
	{
		return BigData(INT64(0));
	}

	if (bigdata._strData == "-1" || bigdata._strData == "+1")    //处理除数为+1 -1的情况
	{
		string ret = _strData;

		if (_strData[0] != bigdata._strData[0])
		{
			ret[0] = '-';
		}
		return BigData(ret.c_str());
	}

	if (_strData.size() == bigdata._strData.size()              //处理除数与被除数一样的情况(除过符号位)
		&& strcmp(_strData.c_str() + 1, bigdata._strData.c_str() + 1) == 0)
	{
		string ret = "+1";

		if (_strData[0] != bigdata._strData[0])
		{
			ret[0] = '-';
		}

		return BigData(ret.c_str());
	}

	return BigData(Div(_strData, bigdata._strData).c_str());
}


string BigData::Add(string left, string right)
{

	int leftsize = left.size();
	int rightsize = right.size();

	if (leftsize < rightsize)
	{
		swap(left, right);
		swap(leftsize, rightsize);
	}

	string iRet;
	iRet.resize(leftsize + 1);
	iRet[0] = left[0];
    int step = 0;         //进位

	for (int i = 1; i < leftsize; i++)
	{
		char cRet = left[leftsize - i] - '0' + step;

		if (i < rightsize)
		{
			cRet += right[rightsize - i] - '0';
		}

		iRet[leftsize - i + 1] = cRet % 10 + '0';

		step = cRet/10;
	}
	iRet[1] = step + '0';

	return iRet;

}


string BigData::Sub(string left, string right)
{
	int leftsize = left.size();
	int rightsize = right.size();

	char cSymbol = '+';
	//10 - 11 = -1
	//-3 - -7 = 4
	if (leftsize < rightsize || leftsize == rightsize && left<right)
	{
		swap(left, right);
		swap(leftsize, rightsize);
		if (cSymbol == '+')
		{
			cSymbol = '-';
		}
		else
		{
			cSymbol = '+';
		}
	}

	string strRet;
	strRet.resize(left.size());
	strRet[0] = cSymbol;


	for (int Idx = 1; Idx < leftsize; ++Idx)
	{
		char cRet = left[leftsize - Idx] - '0';
		if (Idx < rightsize)
		{
			cRet -= right[rightsize - Idx] - '0';
		}

		if (cRet < 0)
		{
			left[leftsize - Idx - 1] -= 1;
			cRet += 10;
		}

		strRet[leftsize - Idx] = cRet + '0';
	}

	return strRet;
}


string BigData::Mul(string left, string right)
{
	char cSymbol = '+';
	if (left[0] != right[0])
	{
		cSymbol = '-';
	}
	int leftsize = left.size();
	int rightsize = right.size();

	if (leftsize < rightsize)
	{
		swap(left, right);
		swap(leftsize, rightsize);
	}

	string sRet;
	sRet.assign(leftsize + rightsize - 1,'0');
	sRet[0] = cSymbol;
	int iDataLen = sRet.size();
	int ioffset = 0;

	for (int iLIdx = 1; iLIdx < leftsize; iLIdx++)
	{
		char cLeft = left[leftsize - iLIdx] - '0';
		char cStep = 0;
		if (cLeft == '0')
		{
			ioffset++;
			continue;
		}

		for (int iRIdx = 1; iRIdx < rightsize; iRIdx++)
		{
			char cRet = cLeft*(right[rightsize - iRIdx] - '0') + cStep;
			cRet += sRet[iDataLen - iRIdx - ioffset] - '0';
			sRet[iDataLen - iRIdx - ioffset] = (cRet % 10 + '0');
			cStep = cRet/10;
		}
		sRet[iDataLen - rightsize - ioffset] += cStep;
		ioffset++;
	}
	return sRet;
}

string BigData::Div(string left, string right)
{
	string sRet;
	sRet.append(1, '+');
	if (left[0] != right[0])
	{
		sRet[0] = '-';
	}

	char* pLeft = (char*)(left.c_str() + 1);
	char* pRight = (char*)(right.c_str() + 1);
	int DataLen = right.size() - 1;
	int Lsize = left.size() - 1;

	for (int iIdx = 0; iIdx < Lsize;)
	{
		if (*pLeft == '0')
		{
			sRet.append(1, '0');
			pLeft++;
			iIdx++;
			continue;
		}

		if (!IsLeftStrBig(pLeft, DataLen, pRight, right.size() - 1))
		{
			sRet.append(1, '0');
			DataLen++;
			if (DataLen + iIdx > Lsize)
			{
				break;
			}
		}
		else
		{
			sRet.append(1, subloop(pLeft, DataLen, pRight, right.size() - 1));

			while (*pLeft == '0' && DataLen > 0)
			{
				pLeft++;
				iIdx++;
				DataLen--;
			}

			DataLen++;
			if (DataLen + iIdx > Lsize)
			{
				break;
			}
		}
	}
	return sRet;
}


bool BigData::IsLeftStrBig(const char* pLeft, int Lsize, const char* pRight, int Rsize)
{
	if (Lsize > Rsize || (Lsize == Rsize && strcmp(pLeft, pRight) >= 0))
	{
		return true;
	}
	else
	{
		return false;
	}
}

char BigData::subloop(char* pLeft, int Lsize, char* pRight, int Rsize)
{
	assert(pLeft && pRight);

	char cRet = '0';

	while (1)
	{
		if (!IsLeftStrBig(pLeft, Lsize, pRight, Rsize))
		{
			break;
		}

		int LDataLen = Lsize - 1;
		int RDataLen = Rsize - 1;

		while (LDataLen >= 0 && RDataLen >= 0)
		{
			char ret = pLeft[LDataLen] - '0';
			ret -= pRight[RDataLen] - '0';

			if (ret < 0)
			{
				pLeft[LDataLen - 1] -= 1;
				ret += 10;
			}

			pLeft[LDataLen] = ret + '0';
			LDataLen--;
			RDataLen--;
		}

		while (*pLeft == '0' && Lsize > 0 )
		{
			pLeft++;
			Lsize--;
		}
		cRet++;
	}
	return cRet;
}
3.函数调用部分:main.cpp

#include"BigData.h"


void Test1()  //除法
{
	BigData b1("222222222222222222222222222222222222222222222222222222222222");
	BigData b2("33");
	          //8898989898989899989898990
	BigData b3("06734006734006734006734006734006734006734006734006734006734");
	cout << b3 << endl;

	cout << b1 << endl;
	cout << b2 << endl;
	cout << b1/b2 << endl;
}


void Test2()  //减法/加法
{
	/*BigData b1("1234567890123456789");
	BigData b2("-9999");
	cout << b1 - b2 << endl;*/

	/*BigData b1("1234567890123456789");
	BigData b2("9999");
	cout << b1 + b2 << endl;*/


	/*BigData b1("1234567890123456789");
	BigData b2("9999");
	cout << b1 - b2 << endl;*/

	BigData b1(1234567890123456789);
	BigData b2("9999");
	cout << b1 - b2 << endl;
}


void Test3()    //乘法
{
	BigData b1("123456789012349999");
	BigData b2("9999");
	cout << b1 * b2 << endl;
}


void FunTest1()
{
	BigData b1("999999999999999999999999999999999999999999999");       // BigData(const char* cData);
	BigData b2(99);         //BigData(INT64 x);
	cout << b1 << endl;
	cout << b2 << endl;          //	friend ostream& operator<<(ostream& out, const BigData& bigdata);
	cout << b1 / b2 << endl;

}


void FunTest2()
{
	BigData b1(12345678);       
	BigData b2(12345678);
	cout << b1 + b2 << endl;   //BigData BigData::operator+(const BigData& bigdata);
}

int main()
{
	//Test1();
	//Test2();
	//Test3();
	//FunTest1();
	FunTest1();
	system("pause");
	return 0;
}





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