C++ 将双精度转换为无符号长C++；

我正在做一个家庭作业，到目前为止，除了“海王星”外，所有的东西都打印出来了。其他的选择都很好，可以打印出它们应该是的数字，但是海王星打印出正确的数字，但是作为负片。有人告诉我把双冠王投给长传，但我相信我投了，这没有什么区别。任何帮助或指导都将不胜感激。我会附上我的代码，你们可以看看。另一件事是当海王星被选为“h”时，选择应该是“h”，那么重量是160，速度是595。此外，以小时为单位打印的旅行时间数字为4537815天189076年518.02年。小时和天数的计算结果是正确的，除了最后一个数字需要在我的代码中四舍五入一，年份的计算结果是正确的，除了它是负数

#include <iostream>
#include <iomanip>
#include <cmath>
#include <string>
using namespace std;

int main()
{
    char selection;
    double weight = 0.0;
    double speed = 0.0;
    double surfGrav;
    double distEarthToSun  = 93 * 1000000;
    double distfromSun = 0.0;
    double newSunDist;
    double newWeight;
    double distFromPlanets;
    // double travelTime;
    double travelTimeHours;
    double travelTimeDays;
    double travelTimeYears;
    string planetName;

    cout << "Welcome to INTERPLANETARY TRAVEL PROGRAM!\n";
    cout << "This program enables you to find out your travel time to the planet\n" 
         << "you want to travel to as well as your weight on that planet.\n";
    cout << "Please enjoy the program and find the perfect planet for you!\n";
    cout << '\n';
    cout << '\n';
    cout << "INTERPLANETARY TRAVEL MENU\n";
    cout << "--------------------------\n";
    cout << "a) Mercury\n";
    cout << "b) Venus\n";
    cout << "c) Earth\n";
    cout << "d) Mars\n";
    cout << "e) Jupiter\n";
    cout << "f) Saturn\n";
    cout << "g) Uranus\n";
    cout << "h) Neptune\n";
    cout << "q) quit\n";
    cout << '\n';
    cout << "Select a planet to travel to or q to quit the program: \n";
    cin >> selection;

    if (selection >= 'a' && selection <= 'h')
    {
        cout << "Please enter your weight (in lbs): \n";
        cin >> weight;
        cout << "Please enter the speed (in mile per hour) that you would like to travel at: \n";
        cin >> speed;
    }

    if (selection == 'a')
    {
        planetName = "Mercury";
        surfGrav = 0.27;
        distfromSun = 36;
    }
    else if (selection == 'b')
    {
        planetName = "Venus";
        surfGrav = 0.86;
        distfromSun = 67;
    }
    else if (selection == 'c')
    {
        planetName = "Earth";
        surfGrav = 1.00;
        distfromSun = 93;
    }
    else if (selection == 'd')
    {
        planetName = "Mars";
        surfGrav = 0.37;
        distfromSun = 141;
    }
    else if (selection == 'e')
    {
        planetName = "Jupiter";
        surfGrav = 2.64;
        distfromSun = 483;
    }
    else if (selection == 'f')
    {
        planetName = "Saturn";
        surfGrav = 1.17;
        distfromSun = 886;
    }
    else if (selection == 'g')
    {
        planetName = "Uranus";
        surfGrav = 0.92;
        distfromSun = 1782;
    }
    else if (selection == 'h')
    {
        planetName = "Neptune";
        surfGrav = 1.44;
        distfromSun = 2793;
    }
    else if (selection == 'q')
    {
       cout << "You have chosen to quit the program. Thank you for using the program!\n";
        return 0;
    }
    else
    {
        cout << "You have entered an invalid selection.\n";
        return 0;
    }

    newWeight = weight * surfGrav;
    newSunDist = distfromSun * 1000000;
    unsigned long l1 = newSunDist;

    if (selection <= 'a' || selection >= 'h')
    {
        distFromPlanets = distEarthToSun - l1;
    }
    else
    {
        distFromPlanets = l1 - distEarthToSun;
    }

    travelTimeHours = distFromPlanets/speed;
    travelTimeDays = travelTimeHours/24.0;
    travelTimeYears = travelTimeDays/365.0;

    cout <<'\n';
    cout << "INTERPLANETARY TRAVEL:  Earth to " << planetName << '\n';
    cout << "--------------------------------------------------\n";
    cout << fixed << setprecision(2) << "Your weight on " << planetName << ":      " << newWeight << " lbs\n";
    cout << '\n';
    cout << "Your travel time to " << planetName << ":\n";
    cout << fixed << setprecision(2) << "    " << "In Hours: " << (long int)(travelTimeHours + 0.5) << " hours\n";
    cout << fixed << setprecision(2) << "    " << "In Days : " << (long int)(travelTimeDays + 0.5) << " days\n";
    cout << fixed << setprecision(2) << "    " << "In Years : " << travelTimeYears << " years\n";
    cout << '\n';
    return 0;
}

#包括
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#包括
使用名称空间std；
int main（）
{
字符选择；
双倍重量=0.0；
双速=0.0；
双曲面曲面；
双distEarthToSun=93*1000000；
与太阳的双距离=0.0；
双新闻；
双倍新重量；
双距行星；
//双倍旅行时间；
双倍旅行时间；
双倍旅行天数；
双旅行时间年；
字符串planetName；
问题出在你的变量
distFromPlanets
上，它分解为-2.7e+9，因为
distEarthToSun=9.3e+7
和
newsnud=2.8e+9
。因此
9.3e+7-2.8e+9
大约等于
-2.8e+9
。我不是天文学家，但如果你把if语句改为
if>（选择“h”）
海王星的计算结果将解析为
2.8e+9-9.3+7+2.7e+9
。再说一遍，我不是天文学家，所以我不确定这是否是你应该计算的。
伙计，检查你的返回键，我想它按了两下。在
travelTimeYears=travelTimeDays/365.0；
上设置一个断点。然后跨过那条线。然后将鼠标悬停在
travelTimeYears
和
travelTimeDays
上，告诉我们它们是什么。为什么代码中的空格要加倍？这并不能让代码更清晰，反而让代码读起来很痛苦。