就一个简单的大数计算

本文主要是介绍就一个简单的大数计算，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

也只是刚刚写出了加法，用的是1 000 000 000进制，不过发现对于加法还不如用最基本的方法方便。用1 000 000 000进制的方便也就在于处理乘法和除法了。计算机做乘除运算还是比较耗时的。

#include <random>
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <utility>
using namespace std;
const int MaxNum=1000000000; //进制
class BigNumCalcu{
public:const static int N=9;BigNumCalcu():num_1(""),result(""),numSize_1(0),numSize_2(0){  //initnum_2="";fopen.open("num.txt");}string patchZero(int M); //补0void getInput();   //读取数据void SplitNum(); void Sum();      //加法string Sub();      //减法void Multi();    //乘法string Div();      //除法void randomData();
private:fstream fopen;vector<int> BitNum_1,BitNum_2;string num_1,num_2,result;unsigned int numSize_1;unsigned int numSize_2;
};void BigNumCalcu::getInput(){for(int i=0;i!=5;++i){result="";BitNum_1.clear();BitNum_2.clear();fopen>>num_1>>num_2;cout<<"num_1: "<<num_1<<"  num_2: "<<num_2<<endl;SplitNum();Sum();}
}
void BigNumCalcu::SplitNum(){numSize_1=(num_1.size()%9==0) ? num_1.size()/9 : num_1.size()/9+1;numSize_2=(num_2.size()%9==0) ? num_2.size()/9 : num_2.size()/9+1;//splitif(numSize_1==num_1.size()/9)for(int index=1;index<=numSize_1;++index)BitNum_1.push_back(std::stoi(num_1.substr(num_1.size()-index*BigNumCalcu::N,9)));elsefor(int index=1;index<=numSize_1;++index){if(index==numSize_1)BitNum_1.push_back(std::stoi(num_1.substr(0,num_1.size()-(index-1)*BigNumCalcu::N)));elseBitNum_1.push_back(std::stoi(num_1.substr(num_1.size()-index*BigNumCalcu::N,9)));        }if(numSize_2==num_2.size()/9)for(int index=1;index<=numSize_2;++index)BitNum_2.push_back(std::stoi(num_2.substr(num_2.size()-index*BigNumCalcu::N,9)));elsefor(int index=1;index<=numSize_2;++index){if(index==numSize_2)BitNum_2.push_back(std::stoi(num_2.substr(0,num_2.size()-(index-1)*BigNumCalcu::N)));elseBitNum_2.push_back(std::stoi(num_2.substr(num_2.size()-index*BigNumCalcu::N,9)));        }
}string BigNumCalcu::patchZero(int M){auto it=std::to_string(M).size();string temp=std::to_string(M);if(it<BigNumCalcu::N){for(;it<BigNumCalcu::N;it++)temp="0"+temp;return result=temp+result;}elsereturn result=std::to_string(M);
}void BigNumCalcu::Sum(){int min=std::min(numSize_1,numSize_2);int index=0;  //进位int sum=0;//如果兩個數字具有相同的位数//如果两个数字位数不一样if(min==numSize_1)for(int count=min;count<numSize_2;++count)if((sum=BitNum_2[count]+index)>=MaxNum){index=1;result=patchZero(sum-MaxNum);}else{index=0;result=patchZero(sum);}elsefor(int count=min;count<numSize_1;++count)if((sum=BitNum_1[count]+index)>=MaxNum){index=1;result=patchZero(sum-MaxNum);}else{index=0;result=patchZero(sum);}//如果最高位也需要进位if(index==1)result="1"+result;cout<<result<<endl;
}int main(int argc,char **argv){BigNumCalcu Calc;Calc.getInput();return 0;
}

下面是一个python测试。因为python已经自带大整数计算了

__author__='MarkLiang'
#coding=utf-8fopen=open('num.txt','r')
for num1 in fopen:num2=fopen.readline();print("result: ",int(num1)+int(num2))fopen.close()

至于乘法和除法，我有空在写吧。

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