浮点数的大数问题

#include <iostream>
#include <string>
#include <algorithm>
#include <stdio.h>

using namespace std;
int part_carrier;

struct Float {
    string num_int;
    string num_part;

    Float(string &num_int, string &num_part) :
            num_int(num_int), num_part(num_part) {};

    Float() {};
};

Float getFloat(string &str) {
    int ix = str.find('.');
    string num1_int, num1_part;
    //第一个整数处理
    if (ix == string::npos) {// 说明没有小数部分
        num1_int = str;
        num1_part = "";
    } else {
        num1_int = str.substr(0, ix);
        num1_part = str.substr(ix + 1);
    }
    return Float(num1_int, num1_part);
}

string getpart(string &part1, string &part2) {
    //这个和整数运算是有区别的
    if (part1.size() < part2.size()) {
        swap(part1, part2);
    }
    int carrier = 0;
    string res;
    for (int i = part2.size() - 1; i >= 0; --i) {
        int n = (part1[i] - '0') + (part2[i] - '0') + carrier;
        carrier = n / 10;
        n = n % 10;
        res.push_back(n + '0');
    }
    part_carrier = carrier;
    for (int i = part2.size(); i < part1.size(); ++i) {
        res.insert(0, 1, part1[i]);
    }
    //为了保证同意，反转
    reverse(res.begin(), res.end());
    return res;
}

string getint(string &num1, string &num2) {
    reverse(num1.begin(), num1.end());
    reverse(num2.begin(), num2.end());
    if (num1.size() < num2.size()) {
        swap(num1, num2);
    }
    string res;
    int carrier = part_carrier;
    for (int i = 0; i < num2.size(); ++i) {
        int n = (num1[i] - '0') + (num2[i] - '0') + carrier;
        carrier = n / 10;
        n = n % 10;
        res.push_back(n + '0');
    }
    for (int i = num2.size(); i < num1.size(); ++i) {
        int n = (num1[i] - '0') + carrier;
        carrier = n / 10;
        n = n % 10;
        res.push_back(n + '0');
    }
    if (carrier != 0) {
        res.push_back(carrier + '0');
    }
    part_carrier = 0;
    return res;
}

int main() {
//    freopen("../in.txt", "r", stdin);
    string num1, num2;
    while (cin >> num1 >> num2) {
        //小数部分和整数部分分开计算
        Float aFloat = getFloat(num1);
        Float bFloat = getFloat(num2);
        //先计算小数部分
        Float res;
        if (aFloat.num_part == "") {
            res.num_part = bFloat.num_part;
        } else if (bFloat.num_part == "") {
            res.num_part = aFloat.num_part;
        } else {
            res.num_part = getpart(aFloat.num_part, bFloat.num_part);
        }
        //小数部分结束
        res.num_int = getint(aFloat.num_int, bFloat.num_int);
        //整数部分和小数部分都算完，准备打印
        //整数部分
        for (int i = res.num_int.size()-1; i >= 0; --i) {
            cout<<res.num_int[i];
        }
        int len = res.num_part.size()-1;
        while (len>=0&&res.num_part[len]=='0'){
            len--;
        }
        if (len>=0){
            cout<<".";
            for (int i = 0; i <= len; ++i) {
                cout<<res.num_part[i];
            }
        }
        cout<<endl;
    }
}