Debug Assertion在動態數組上失敗

Question

所以這裏是我的一個簡單動態數組的工作代碼。這必須是一個非常入門級的數據結構實現一個示例代碼：

#include <iostream> 
using namespace std; 

class AdvancedArray { 
public: 
    AdvancedArray(); 
    ~AdvancedArray(); 
    int get_size() const; // get the number of elements stored 
    double& at(int idx) const; // access the element at idx 
    void push_back(double d); // adds a new element 
    void remove(int idx); // remove the element at idx 
    void clear(); // delete all the data stored 
    void print() const; 

private: 
    double* elements; 
    int size; 
}; 

int main() 
{ 
    AdvancedArray* arr = new AdvancedArray(); 
    cout << "The Array Size is: " << arr->get_size() << endl; 
    cout << "Pusing Values: 1.2, 2.1, 3.3, 4.5 in the Array. " << endl; 
    arr->push_back(1.2); 
    arr->push_back(2.1); 
    arr->push_back(3.3); 
    arr->push_back(4.5); 
    arr->print(); 
    cout << "The Array Size is: " << arr->get_size() << endl; 
    cout << "The Element at Index 2 is: " << arr->at(2) << endl; 
    cout << "Deleting Values: 2.1 from the Array. " << endl; 
    arr->remove(1); 
    cout << "The Array Size is: " << arr->get_size() << endl; 
    arr->print(); 
    cout << "Clearing the Array: " << endl; 
    arr->clear(); 
    cout << "The Array Size is: " << arr->get_size() << endl; 
    arr->clear(); 
    return 0; 
} 

AdvancedArray::AdvancedArray() 
{ 
    size = -1; 
    elements = new double[100]; //Maximum Size of the Array 
} 

AdvancedArray::~AdvancedArray() 
{ 
    delete[] elements; 
} 

int AdvancedArray::get_size() const 
{ 
    if(size < 0) 
    { 
     return 0; 
    } 
    return size; 
} 

double & AdvancedArray::at(int idx) const 
{ 
    if (idx < 100 && idx >= 0 && size > 0) { 
     return elements[idx]; 
    } 
    cout << "Index Out of Bounds." << endl; 
} 

void AdvancedArray::push_back(double d) 
{ 
    if (size >= 100) 
    { 
     cout << "Overflow Condition. No More Space!" << endl; 
    } 
    else 
    { 
     elements[++size] = d; 
     cout << "Element Pushed In Stack Successfully!" << endl; 
    } 
} 

void AdvancedArray::remove(int idx) 
{ 
    if (size >= 100 || size < 0) 
    { 
     cout << "No Such Element Exists!" << endl; 
    } 
    else 
    { 
     for(int i = idx; i <size; i++) 
     { 
      elements[idx] = elements[idx + 1]; 
     } 
     size--; 
     cout << "Element Deleted In Stack Successfully!" << endl; 
    } 
} 

void AdvancedArray::clear() 
{ 
    delete[] elements; 
    size = -1; 
} 

void AdvancedArray::print() const 
{ 
    cout << "[ "; 
    for(int i = 0; i <= size; i++) 
    { 
     cout << elements[i] << " "; 
    } 
    cout << "]" << endl; 
} 

所以每次我嘗試運行這段時間我有2個問題：

我的代碼有什麼問題？爲什麼堆被損壞（我搜索了錯誤代碼，這就是所有人都說的）？我的代碼是否執行一些主要的訪問違規？我正在使用VS2015。

Answer 1

你做delete [] elements 倍之間沒有設置elements到nullptr。這導致第二次（和第三次）未定義行爲。

Answer 2

當size == 99，下面這段代碼試圖訪問elements[100]：

if (size >= 100) 
{ 
    cout << "Overflow Condition. No More Space!" << endl; 
} 
else 
{ 
    elements[++size] = d; 
    cout << "Element Pushed In Stack Successfully!" << endl; 
} 

您需要更改++size到size++。