Question

我正在尝试释放动态内存但我收到了错误。我需要一些帮助来指出我的代码的哪一部分导致错误。

我有析构函数来释放两个动态数组。删除析构函数我没有错误。

错误：_BLOCK_TYPE_IS_VALID（pHEAD-＆gt; nBlockUse）

分数等级：

class Scores
{
private:
    int numOfTest;
    double *scoresArray = nullptr;
    double scoreAvg;
    double *scoreSort = nullptr;
public:
    Scores(int);
    ~Scores();
    void setNumOfTest();
    int getNumOFTest();
    void setScores();
    double* getScores();
    void setSort();
    double* getSort();
    void setScoreAvg();
    double getScoreAvg();
};

Scores::Scores(int num)
{
    scoresArray = new double [num];
    scoreSort = new double[num];
    numOfTest = num;
}

Scores::~Scores()
{
    delete [] scoresArray;
    delete [] scoreSort;
    scoresArray = nullptr;
    scoreSort = nullptr;
}



void Scores::setNumOfTest()
{
    // Verify number of test scores is positive
    while (numOfTest <= 0)
    {
        cout << "The number of test need to be postive." << endl;
        cout << "Enter another number: ";
        cin >> numOfTest;
    }
}

int Scores::getNumOFTest()
{
    return numOfTest;
}

void Scores::setScores()
{
    double scores;
    int size = getNumOFTest();
    //scoresArray = new double[size];

    for (int i = 0; i < numOfTest; i++)
    {
        cout << "Enter test score " << i + 1 << ": ";
        cin >> scores;

        // Verify if score enter is positive
        while (scores < 0)
        {
            cout << "Negative scores are not allowed." << endl;
            cout << "Enter another score for this test: ";
            cin >> scores;
        }

        scoresArray[i] = scores;
    }
}

double* Scores::getScores()
{
    //double *sa = scoresArray; 
    //return sa;
    return scoresArray;
}

void Scores::setSort()
{
    int size = getNumOFTest();
    //scoreSort = new double[size];
    scoreSort = getScores();

    for (int i = 0; i < size; i++)
    {
        int smallPos = i;
        double smallest = scoreSort[smallPos];

        for (int j = i + 1; j < size; j++)
        {
            if (scoreSort[j] < scoreSort[smallPos])
            {
                smallPos = j;
                smallest = scoreSort[smallPos];
            }
        }

        scoreSort[smallPos] = scoreSort[i];
        scoreSort[i] = smallest;
    }
}

double* Scores::getSort()
{
    //double *ss = scoreSort;
    //return ss;
    return scoreSort;
}

void Scores::setScoreAvg()
{
    int size = getNumOFTest();

    for (int i = 0; i < size; i++)
    {
        scoreAvg += scoresArray[i];
    }

    scoreAvg /= size;
}

double Scores::getScoreAvg()
{
    return scoreAvg;
}

主：

int main()
{
    int numOfTest;

    cout << "How many test scores will you enter" << endl;
    cin >> numOfTest;

    Scores s(numOfTest);

    s.setNumOfTest();
    s.setScores();
    s.setSort();
    s.setScoreAvg();

    double y = s.getScoreAvg();
    double *x = nullptr;
    x = new double[numOfTest];
    x = s.getSort();

    cout << "sort" << endl;
    for (int i = 0; i < numOfTest; i++)
    {
        cout << x[i] << "\n";
    }

    cout << "avg" << endl;
    cout << y;
    delete[] x;
    x = nullptr;
    //s.Scores1();

    return 0;
}

Answer 1

您看到的是双重删除。一个明显的问题是，您在这里获得了一个指向对象s的动态分配数组scoresArray的指针：

x = s.getSort(); // also leaks memory previously pointed at by x

然后你打电话给delete[]：

delete[] x; // calls delete[] on s.scoresArray

但s对象也在其析构函数中调用delete[]。这会导致双重删除。

除此之外，代码中可能还有其他错误。

请注意，您可以通过不显式使用动态分配来避免此问题，而是依赖std::vector<double>之类的类型。

Answer 2

问题在于Scores::setSort：

中的这一行

scoreSort = getScores();

getScores()返回scoresArray。所以现在scoreSort和scoresArray指向同一个动态分配的块。当您尝试删除它们时，您将两次删除相同的块。

您应该将scoresArray的内容复制到scoreSort，然后对scoreSort进行排序，而不是分配指针。

free dynamic array memory error：_BLOCK_TYPE_IS_VALID

2 个答案: