抛出“std::out_of_range”实例后调用终止

我绝对是编程初学者。我在构建以下代码时遇到此错误。

error: terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 8) >= this->size() (which is 8) Aborted (core dumped)

#include<iostream>
#include<vector>
#include<string>
#include<iomanip>
using namespace std;
int main()
{
    cout<<"\n Welcome to space travel calculation program";

    string cPlanet, name;
    double weight, speed, tTime, nWeight;
    int num;
    vector<string> planet;
    vector<int> distance;
    vector<double> sGravity;

    planet.push_back("Mercury");
    distance.push_back(36);
    sGravity.push_back(0.27);

    planet.push_back("Venus");
    distance.push_back(67);
    sGravity.push_back(0.86);

    planet.push_back("Earth");
    distance.push_back(93);
    sGravity.push_back(1.00);

    planet.push_back("Mars");
    distance.push_back(141);
    sGravity.push_back(0.37);

    planet.push_back("Jupiter");
    distance.push_back(483);
    sGravity.push_back(2.64);

    planet.push_back("Saturn");
    distance.push_back(886);
    sGravity.push_back(1.17);

    planet.push_back("Uranus");
    distance.push_back(1782);
    sGravity.push_back(0.92);

    planet.push_back("Neptune");
    distance.push_back(2793);
    sGravity.push_back(1.44);
    num=planet.size();

    cout<<"\n Please tell me your name: ";
    getline(cin,name);


    cout<<"\n Please choose which planet you want to travel to from the following list:"
        <<"\n 1.Mercury"
        <<"\n 2.Venus"
        <<"\n 3.Earth"
        <<"\n 4.Mars"
        <<"\n 5.Jupiter"
        <<"\n 6.Saturn"
        <<"\n 7.Uranus"
        <<"\n 8.Neptune       :";
    getline(cin,cPlanet);

    cout<<"\n What is your weight on Earth?";
    cin>>weight;

    cout<<"\n At what speed do you wish to travel? :";
    cin>>speed;

    if(cPlanet==planet.at(num))
    {
        tTime=(distance.at(num))/speed;
        nWeight=weight*sGravity.at(num);

        cout<<"\n Your Name: "<<name
            <<"\n Weight On Earth: "<<weight
            <<"\n Planet you wish to visit: "<<cPlanet
            <<"\n The speed you will be travelling at: "<<speed
            <<"\n Total time it will take to reach "<<planet.at(num)<<": "<<tTime
            <<"\n Your weight on "<<planet.at(num)<<": "<<nWeight;
    }

    return 0;
}

C++ 中的数组和向量索引从 0 到 size - 1。因此，当你说

num=planet.size();

然后

if(cPlanet==planet.at(num))

您正在尝试访问一过终点向量的planet. The at然后成员函数抛出类型的异常std::out_of_range它永远不会被捕获，并且您的程序因此而终止。

看起来您想要找到与行星名称相对应的矢量索引；你可以这样做std::find http://en.cppreference.com/w/cpp/algorithm/find and std::distance http://en.cppreference.com/w/cpp/iterator/distance如下：

num = std::distance(planet.begin(), std::find(planet.begin(), planet.end(), cPlanet));

这将返回planet.size() if cPlanet没有找到。然而，用一个来实现整个事情可能会更好std::map http://en.cppreference.com/w/cpp/container/map.