Question

我现在很迷茫。我做了一个矢量课。一切都按照我希望的方式运作，直到最后。当调用析构函数时，我收到一条错误消息：Debug assertion failed BLOCK_TYPE_IS_VALID（pHead-＆gt; nblockuse）。我在SO上看过很多类似这样的问题，但我所尝试的却没有用。

.h。

的一部分

private:
    int* _myArray;
    int _size;
    int _capacity;

#include "File.h"

 const string RETURN_CARRIAGE_STR = "\n";
 const string SIZE_STR = "Size ";
 const string CAPACITY_STR = "Capacity ";
 const int INITIAL_CAPACITY = 2;

 int main(void)
{
cout << "\nCreating a vector Sam of size 4.";
MyVector sam( 4 );

cout << "\nPush 12 values into the vector.";
for (int i = 0; i < 12; i++)
    sam.push_back(i);

cout << "\nHere is sam: ";
cout << sam;
cout << "\n---------------\n";

    cout << "\nCreating a vector Joe of size 4.";
MyVector joe( 4 );
cout << "\nPush 6 values into the vector.";
for (int i = 0; i < 6; i++)
    joe.push_back(i * 3);

cout << "\nHere is joe: ";
cout << joe;
cout << "\n---------------\n";

cout << "\nTest the overloaded assignment operator \"joe = sam\": ";
joe = sam;


cout << "\nHere is sam: ";
cout << sam;
cout << "\n---------------\n";

cout << "\nHere is joe: ";
cout << joe;
cout << "\n---------------\n";

// pass a copy of sam by value
PrintV(sam);

cout << endl;
system("PAUSE");
 }

 void PrintV(MyVector v)
 {
cout << "\n--------------------\n";
cout << "Printing a copy of a vector\n";
cout << v;
 }

 // Default Constructor
 MyVector::MyVector()
 {
_myArray = new int[INITIAL_CAPACITY];
_size = 0;
_capacity = INITIAL_CAPACITY;
//cout << "Default Constructor" << endl;
 }

 MyVector::MyVector(int aSize)
 {
_myArray = new int[aSize];
_size = 0;
_capacity = aSize;

//cout << "Parameterized Constructor" << endl;
 }

 MyVector::~MyVector()
 {
if(_myArray != NULL)
{
    delete[] this->_myArray; //  --------------This is where I get an error
    this->_myArray = NULL;
}

//cout << "Destructor" << endl;
 }


 int MyVector::GetSize()
 {
return _size;
//cout << " size";
 }

 int MyVector::GetCapacity()
 {
return _capacity;
//cout << _capacity << " capacity" << endl;
 }

 void MyVector::Clear()
 {
int* resize_arr = new int[INITIAL_CAPACITY];
delete[] _myArray;
_myArray = resize_arr;
_capacity = INITIAL_CAPACITY - 1;
_size = 0;
 }

 void MyVector::push_back(int newValue)
 {
if(_size < _capacity)
{
    _myArray[_size] = newValue;
}
else  {
    int* resize_arr = new int[_capacity*2];
    for(int i = 0; i <= _size; i++)
        resize_arr[i] = _myArray[i];

    resize_arr[_size] = newValue;
    delete[] _myArray;
    _myArray = resize_arr;
    _capacity = _capacity * 2;
}
_size++;
//cout << _size << " size" << endl;
 }

 int MyVector::at(int idx)
 {
return _myArray[idx];
//cout << _myArray[idx] << " value at index" << endl;
 }

 ostream& operator<<(ostream& os, MyVector& vec)
 {
ostringstream convert;
ostringstream convertCap;
convert << vec.GetSize();
string sizeConverted = convert.str();
convertCap << vec.GetCapacity();

string capConverted = convertCap.str();
string firstTemp = "";
firstTemp = SIZE_STR + sizeConverted  + RETURN_CARRIAGE_STR + CAPACITY_STR + capConverted + RETURN_CARRIAGE_STR;

for(int idx = 0; idx < vec.GetSize(); idx++)
{
    string secondTemp = "";
    ostringstream convertSize;
    convertSize << vec.at(idx);
    string vecAtIdx = convertSize.str();
    secondTemp = vecAtIdx + RETURN_CARRIAGE_STR;
    cout << secondTemp;
}

os <<  firstTemp;
return os;
 }

 MyVector& MyVector::operator=(MyVector& setterVect)
 {
delete [] _myArray;

//MyVector* mPtr = new MyVector();

_myArray = setterVect._myArray;
_capacity = setterVect._capacity;
_size = setterVect._size;

return *this;
 }

Answer 1

_myArray = setterVect._myArray;

您的副本分配运算符已损坏。在该运算符之后，两个实例具有_myArray的相同值。因此，只要一个被破坏，另一个就会留下指向不再存在的东西。

故事的寓意 - 使用std::vector。

Answer 2

错误意味着堆损坏。有很多方法可以破坏堆。就像大卫在上面解释的那样，释放一大块记忆然后写入它就是一种方式。

大多数堆在您的大块内存之前和之后存储一些字节的簿记信息。如果您的代码行为异常并更改了堆数据，则会出现此类错误。

调试断言从解构器失败BLOCK_TYPE_IS_VALID（pHead-> nblockuse）

2 个答案: