Question

我正在尝试运行以下代码，但只要创建了继承类的对象就会崩溃。

程序正常工作，直到创建继承的类对象，但在＆＃34; Student * s＆＃34;之后发生了分段错误。行被执行。

以下是代码：

#include <iostream>
#include <vector>

using namespace std;

class Person
{
protected:
    string firstName;
    string lastName;
    int id;
public:
    Person(string firstName, string lastName, int identification)
    {
        this->firstName = firstName;
        this->lastName = lastName;
        this->id = identification;
    }
    void printPerson()
    {
        cout << "Name: " << lastName << ", " << firstName << "\nID: " << id
                << "\n";
    }

};

class Student: public Person
{
private:
    vector<int> testScores;
public:
    Student(string f, string l, int i, vector<int>& scores) :
            Person(firstName, lastName, id)
    {
        this->firstName = f;
        this->lastName = l;
        this->id = i;
        this->testScores = scores;
    }

    char calculate()
    {
        vector<int>::iterator it;
        int sum = 0;
        for (it = testScores.begin(); it != testScores.end(); it++)
        {
            sum += *it;
        }
        int avg = sum / (testScores.size());
        if (avg >= 90 && avg <= 100)
            return 'O';
        else if (avg >= 80 && avg < 90)
            return 'E';
        else if (avg >= 70 && avg < 80)
            return 'A';
        else if (avg >= 55 && avg < 70)
            return 'P';
        else if (avg >= 40 && avg < 55)
            return 'D';
        else
            return 'T';

    }
};

int main()
{
    string firstName;
    string lastName;
    int id;
    int numScores;
    cin >> firstName >> lastName >> id >> numScores;
    vector<int> scores;
    for (int i = 0; i < numScores; i++)
    {
        int tmpScore;
        cin >> tmpScore;
        scores.push_back(tmpScore);
    }
    cout << "Calling\n";
    Student* s = new Student(firstName, lastName, id, scores);
    cout << "Done\n";
    s->printPerson();
    cout << "Grade: " << s->calculate() << "\n";
    return 0;
}

Answer 1

    Student(string f, string l, int i, vector<int>& scores) :
            Person(firstName, lastName, id)

使用Person自己的firstName，lastName和id成员来构建Person。这可能会或可能不会出现分段错误和繁荣，但肯定会进入未定义的行为。

OP想要更像这样的东西，而不是使用传递的参数：

    Student(string f, string l, int i, vector<int>& scores) :
            Person(f, l, i)
    {
        // all of the members that were set here don't need to be set. 
        // Person did it already
        this->testScores = scores;
    }

可以进一步改进。可以使用the member initializer list初始化testScores。这允许scores立即填入testScores，编译器可以进行各种有趣的优化。

    Student(string f, string l, int i, vector<int>& scores) :
            Person(f, l, i), testScores(scores)
    {
    }

尽可能初始化初始化列表中的成员变量。 `人也可以改进：

    Person(string first, string last, int identification):
        firstName(first),
        lastName(last),
        id(identification)
    {
    }

现在可以找到并修复Rakete1111发现的零除虫病。

分段错误c ++导致程序崩溃

1 个答案: