模板数组中的 C++ 堆损坏

Question

如标题所述，我的 C++ 代码中存在堆损坏问题。我知道有很多主题涉及堆损坏问题，我访问了很多主题，我在很多网站上阅读了很多关于这些问题的内容，我什至使用 Visual Leak Detector 来查找内存的位置泄露。我似乎仍然无法弄清楚为什么会发生堆损坏。

我的代码:

#include <iostream>
#include "stdafx.h"
#include "cstdlib"
#include <vld.h>
#include <math.h>

using namespace std;

template <class T>
class PrioQueue
{
private:
    int size_;
    int tempIndex;
public:
    T *bottom_;
    T *top_;
    PrioQueue(int n =20){
        size_ = n;
        bottom_ = new T[size_];
        top_ = bottom_;
    }
    void push(T c){
        //add the item to the list
        *top_ = c;
        top_++;

        //Save the old stack values in the temp memory
        T* values = bottom_;
        T tempItem;
        int index = num_items();
        cout << "Num items: " << index << endl;
        cout << "1" << endl;
        while(index > 1){
            cout << "2" << endl;
            if(values[index-1] > values[index-2])
            {
                cout << "2b" << endl;
                tempItem = values[index-2];
                values[index-2] = c;
                values[index-1] = tempItem;

            }
            cout << "3" << endl;
            index--;
        }
        cout << "4" << endl;

    }

    // + operator 
    PrioQueue* operator+ (PrioQueue que2)
    {
        PrioQueue<T>* temp = new PrioQueue<T>();
        cout << "Created temporary queue" << endl;
        for(int i = 0; i <num_items(); i++)
        {
            cout << "Element in list: " << bottom_[i] << endl;
            temp->push(bottom_[i]);
            cout << "Temp is now: ";
            temp->print();
        }
        for(int i = 0; i < que2.num_items(); i++)
        {
            cout << "Element in list: " << que2.bottom_[i] << endl;
            temp->push(que2.bottom_[i]);
            cout << "Temp is now: ";
            temp->print();
        }
        cout << "Ran loop" << endl;
        return temp;
    }

    // * operator 
    PrioQueue* operator* (PrioQueue que2)
    {
        PrioQueue<T>* temp = new PrioQueue<T>(); 
        for(int i = 0; i < num_items(); i++)
        {
            for(int j = 0; j < que2.num_items(); j++)
            {
                if(bottom_[i] == que2.bottom_[j])
                {
                    temp->push(bottom_[i]);
                    break;
                }
            }
        }

        return temp;
    }

    friend ostream& operator<< (ostream& output, PrioQueue& q) {
        for(T *element = q.bottom_; element < q.top_; element++)
            output << *element << " | ";
        return output;
    }

    int num_items() {
        return (top_ - bottom_ );
    }
    T pop(){
        top_--;
        return *top_;
    }
    int full() {
        return (num_items() >= size_);
    }
    int empty() {
        return (num_items() <= 0);
    }
    void print(){
        cout << "Print function..." << endl;
        cout << "Stack currently holds " << num_items() << " items: " ;
        for (T *element=bottom_; element<top_; element++) {
            cout << " " << *element;
        }
        cout << "\n";
    }
    ~PrioQueue(){ // stacks when exiting functions
        delete [] bottom_;
    }
};

int main()
{
    PrioQueue<int> *p1 = new PrioQueue<int>(20);
    p1->push(5);
    p1->push(2);
    p1->push(8);
    p1->push(4);
    p1->print(); cout << "\n";

    PrioQueue<int> *p2 = new PrioQueue<int>(5);
    p2->push(33);
    p2->push(66);
    p2->push(8);
    p2->push(5);
    p2->print(); cout << "\n";

    //add them together

    p1->print();
    p2->print();

    ((*p1) + (*p2))->print();
    ((*p1) * (*p2))->print();


    PrioQueue<float> *f1 = new PrioQueue<float>(5);
    f1->push(1.1f);
    f1->push(5.2f);
    f1->push(8.3f);
    f1->push(14.4f);
    f1->push(17.5f);
    f1->print(); cout << "\n";

    PrioQueue<float> *f2 = new PrioQueue<float>(4);
    f2->push(2.2f);
    f2->push(6.7f);
    f2->push(10.3f);
    f2->push(15.6f);
    f2->print(); 
    cout << "\n";

    //add them together
    ((*f1) + (*f2))->print();

    // Multiply them.
    ((*f1) * (*f2))->print();

    cout << "\n";
    cout << p1 << endl;
    cout << f1 << endl;

    cout << "Press any key to exit...";
    cin.get();
    cin.get();

    delete p1;
    delete p2;
    delete f1;
    delete f2;
    return 0;
}

我已经尝试删除所有内容并从头开始。似乎在改变:

    delete [] bottom_;

收件人:

    delete bottom_;

已修复它，但那是在我将值推送到数组之前。

请问有什么问题的请指教。将不胜感激。

提前谢谢你，

Greats Matti Groot。

Answer 1

您提到的更改会导致未定义的行为。如果你用 new[] 得到了一些东西，你必须把它传递给 delete[]。 Plain delete 仅适用于您通过 plain new 获得的内容。

您的运算符 + 和 * 创建新对象并返回指向它的指针。我没有看到任何删除这些对象的尝试，所以难怪你有泄漏。 (无缘无故地返回有义务的指针被认为是糟糕的设计，更何况是来自应该产生对象的对象的操作符。)