Question

我试图在c ++中删除链表中的节点，但是在删除事务后它一直说_pending_tx不是nullptr。另外valgrind说我有内存泄漏，我无法弄清楚

bool BankData::void_transaction(const size_t& customer_id, const size_t& timestamp) { 

bool var8 = false;

if (transaction_exists(customer_id, timestamp) == true)
{
    int blah3 = customerVector.size();
    for (int i = 0; i < blah3; i++)
    {
        if (customerVector.at(i)._customer_id == customer_id)
        {
            if (customerVector.at(i)._pending_txs != nullptr)
            {
                CSE250::dTransactionNode *temp = customerVector.at(i)._pending_txs;
                while (temp->_tx._timestamp != timestamp)
                {
                    temp = temp->_next;
                    if ((temp->_next == nullptr) && (temp->_tx._timestamp != timestamp))
                    {
                        var8 = false;
                    }
                }
                if (temp->_tx._timestamp == timestamp)
                {
                    if ((temp->_prev == nullptr) && (temp->_next == nullptr))         //head and only node
                    {
                        delete  customerVector.at(i)._pending_txs;
                        customerVector.at(i)._pending_txs = nullptr; //after i delete the head and only node i reset it to a nullptr
                        var8 = true;
                    }
                    else if ((temp->_prev == nullptr) && (temp->_next != nullptr))     //head
                    {
                        temp = customerVector.at(i)._pending_txs->_next;
                        delete  customerVector.at(i)._pending_txs;
                        customerVector.at(i)._pending_txs = temp;
                        customerVector.at(i)._pending_txs->_prev = nullptr;
                        var8 = true;
                    }
                    else if ((temp->_prev != nullptr) && (temp->_next == nullptr))    //tail
                    {
                        temp = customerVector.at(i)._pending_txs->_prev;
                        delete  customerVector.at(i)._pending_txs;
                        customerVector.at(i)._pending_txs = temp;
                        customerVector.at(i)._pending_txs->_next = nullptr;
                        var8 = true;
                    }
                    else                                                              //middle node
                    {
                        temp = customerVector.at(i)._pending_txs->_next;
                        customerVector.at(i)._pending_txs->_next->_prev = customerVector.at(i)._pending_txs->_prev;
                        delete  customerVector.at(i)._pending_txs;
                        customerVector.at(i)._pending_txs = temp;
                        //temp->_prev->_next = temp->_next;
                        //temp->_next->_prev = temp->_prev;
                        //temp = nullptr;
                        //delete temp;
                        var8 = true;
                    }
                }
            }
        }
    }
}
return var8;

这是我要删除的节点结构：

namespace CSE250 {
struct dTransactionNode;}

struct CSE250::dTransactionNode {
Transaction _tx;

dTransactionNode* _prev;

dTransactionNode* _next;

dTransactionNode(size_t time, double amount) : _tx(time, amount), _prev(nullptr), _next(nullptr) { }};

我也无法弄清楚为什么当我尝试删除它时，它只会删除时间戳而不是时间戳和数量。所以当我运行我的交易存在功能时，它仍然说部分交易存在。

That's the valgrind message

And those are the error messages I get that say its not pointing to a nullptr after the transaction has been voided even thoguh i set it manually to a null ptr

Answer 1

当你delete某事时，指针不会自动设置为nullptr。这是程序员的责任。阅读Why doesn't delete set the pointer to NULL?

中的更多内容

将指针设置为null时，它不会删除内存。如果你这样做，在你调用delete之前，如果没有用引用它的另一个指针删除内存，你就会产生内存泄漏。

可以使用智能指针，这可以帮到你。

内存泄漏删除节点C ++

1 个答案: