为什么代码会失败并显示“正在释放的指针未分配”？

Question

我有一个错误

12 SIZE: 3 CAPACITY: 4
12 SIZE: 4 CAPACITY: 4
DESTRUCTOR
proj1(53055,0x10121c580) malloc: *** error for object 0x600001ac1110: pointer being freed was not allocated
proj1(53055,0x10121c580) malloc: *** set a breakpoint in malloc_error_break to debug
zsh: abort      /Users/mascai/root_folder/dev/projects/03_cpp_examples/02_ide/build/proj1

我的代码：

template<class T>
class Vector {
public:
    Vector() = default;
    Vector(size_t size) : size_(size), capacity_(size * 2) {
        data_= new T[capacity_];
    }
    Vector(size_t size, const T val) : size_(size), capacity_(size * 2) {
        data_= new T[capacity_];
        for (size_t i = 0; i < size_; ++i) {
            data_[i] = val;
        }
    }
    Vector(const Vector& other) {
        data_ = other.data_;
        size_ = other.size_;
        capacity_ = other.capacity_;
    }
    const Vector& operator=(const Vector<T>& other) {
        data_ = other.data_;
        size_ = other.size_;
        capacity_ = other.capacity_;
        return *this;
    }
    ~Vector() {
        cout << "DESTRUCTOR" << endl;
        if (data_) {
            delete[] data_;
        }
        size_ = 0;
        capacity_ = 0;
    }

    T operator[](size_t idx) const {
        if (idx < size_) {
            return *(data_ + idx);
        }
        throw std::invalid_argument("Inde out of range");
    }

    void push_back(const T& val) {
        size_ += 1;
        if (size_ > capacity_) {
            capacity_ *= 2;
            T* new_data = new T[capacity_];
            for (int i = 0; i < size_ - 1; ++i) {
                *new_data++ = *data_++; 
            }
            delete[] data_;
            data_ = new_data; 
        } else {
            *(data_ + size_ - 1) = val;
        }
    }

    size_t size() const {
        return size_;
    }

    size_t capacity() const {
        return capacity_;
    }

private:
    T* data_ = nullptr;
    size_t size_ = 0;
    size_t capacity_ = 0;
};


int main() {
    Vector<int> v(2, 111);
    assert(v[0] == 111);
    v.push_back(12);
    cout << v[2] << " SIZE: " << v.size() << " CAPACITY: " << v.capacity() << endl;
    v.push_back(12);
    cout << v[3] << " SIZE: " << v.size() << " CAPACITY: " << v.capacity() << endl;
    v.push_back(13);
}

看起来问题与删除的无效使用有关。我应该解决什么问题？

Answer 1

当您添加新元素并需要分配更多内存时，您会遇到以下不幸的序列：

for (size_t i = 0; i < size_ - 1; ++i) {
    *new_data++ = *data_++; 
}
delete[] data_;

当您之后

delete[] data_

时，它不保存原始地址，因此您的程序具有未定义的行为。

我现在还推荐

delete

你的复制构造函数和复制赋值运算符。它们不起作用。