为什么不复制指针时会出错？

Question

以下代码会引发错误。错误在 delete[] pIntArray 错误是 _ASSERTE(_BLOCK_TYPE_IS_VALID(pHead->nBlockUse));:

#include <iostream>

using std::cout;
using std::endl;


int main()
{

    int* pIntArray = new int[50];
    cout << "adding numbers to array ..." << endl;

    for (int i = 0; i < 50; i++)
    {
        pIntArray[i] = i + 10;
    }

    cout << "values in array: " << endl;

    for (int i = 0; i < 50; ++i)
    {
        cout << "integer[" << i << "] = " << *(pIntArray++) << endl;

    }

    cout << "deleting dynamic memory ..." << endl;

    delete[] pIntArray;

    cout << "memory deleted." << endl;

    return 0;
}

但事实并非如此。唯一的区别是我正在复制指针并递增副本：

#include <iostream>

using std::cout;
using std::endl;


int main()
{

    int* pIntArray = new int[50];
    cout << "adding numbers to array ..." << endl;
    int* pCopy = pIntArray;

    for (int i = 0; i < 50; i++)
    {
        pIntArray[i] = i + 10;
    }

    cout << "values in array: " << endl;

    for (int i = 0; i < 50; ++i)
    {
        cout << "integer[" << i << "] = " << *(pCopy++) << endl;

    }

    cout << "deleting dynamic memory ..." << endl;

    delete[] pIntArray;

    cout << "memory deleted." << endl;

    return 0;
}

有人能解释一下原因吗？提前致谢。

Answer 1

因为你正在改变指针的值，所以指针指向的内存地址：

示例 1：

[0][0][0][0][0][0][0][0][0][0][0][0]
                                  ^
                                  |
                                  pIntArray is here

示例 2：

[0][0][0][0][0][0][0][0][0][0][0][0]
 ^                                ^
 |                                |
 pIntArray is here                pCopy is here

您需要delete[] 确切的指针（这是因为大多数 C/C++ 运行时存储在ptr - 1 word 分配的内存大小）

Answer 2

for (int i = 0; i < 50; ++i)
{
    cout << "integer[" << i << "] = " << *(pIntArray++) << endl;

}

cout << "deleting dynamic memory ..." << endl;

delete[] pIntArray;

您使用++ 修改pIntArray 的值，然后将修改后的 值传递给delete[]。您需要将new[] 返回的值准确地传递给delete[]。