Question

我正在研究一个类LinkedList，它看起来像这样：

Linkedlist foo =   Linkedlist();
foo.push_back(3);
foo.push_back(5);

函数push_back创建一个新的LL_element对象（动态分配）。函数pop_back显式删除列表末尾的元素。只要列表不为空，析构函数就会使用函数pop_back。问题是当我创建一个Linkedlist对象时：

Linkedlist* foo = new Linkedlist();
foo->push_back(3);
foo->push_back(5);

当foo超出范围时，析构函数被调用，但Visualstudio仍然给出了LL_elements的内存泄漏。但是，当我动态分配：

bool Linkedlist:: pop_back(int& value) {

//only if the list is not empty, an element can be removed.
if(!this->is_empty()) {

    value = this->last->get_value();
    LL_element* removed = this->last;
    this->last = removed->get_previous();

    if(this->size!=1) {
    this->last->set_next(NULL);
    }

    delete removed; 
    size--;
    return true;
}   

value = 0;
cout << EMPTY_LIST_MESSAGE << endl;
return false;}

void Linkedlist:: push_back(int value)
{

LL_element* to_add = new LL_element(value);

//if there already is a first element, we can ignore it
if(!this->is_empty()) {

    this->last->set_next(to_add);
    to_add->set_previous(last);
    this->last = to_add;
    size++;

}

//if the list is empty --> special case.
else {

    this->first = to_add;
    this->last = to_add;
    size++;

}
}

然后使用'delete'调用析构函数，VS不会给出memoryleaks。

编译器没有正确调用析构函数，或者在堆栈上创建Linkedlist时是否正确使用了默认构造函数？是真的困惑我...

push_back和pop_back的代码：

int main(int argc, const char * argv[]) {

Linkedlist foo; 
foo.push_back(3);
foo.push_back(5);
foo.push_back(6);
foo.push_back(7); 
_CrtDumpMemoryLeaks();
return 0;
}

SSCCE：

Detected memory leaks!
Dumping objects ->
{139} normal block at 0x00A58148, 12 bytes long.
 Data: <            > 00 00 00 00 00 81 A5 00 07 00 00 00 
{138} normal block at 0x00A58100, 12 bytes long.
 Data: <H           > 48 81 A5 00 B8 80 A5 00 06 00 00 00 
{137} normal block at 0x00A580B8, 12 bytes long.
 Data: <     0      > 00 81 A5 00 F0 30 A5 00 05 00 00 00 
{136} normal block at 0x00A530F0, 12 bytes long.
 Data: <            > B8 80 A5 00 00 00 00 00 03 00 00 00 
Object dump complete.
The program '[5592] linkedlist.exe' has exited with code 0 (0x0).

输出：

XCDYouTubeVideoPlayerViewController *videoPlayerViewController = [[XCDYouTubeVideoPlayerViewController alloc] initWithVideoIdentifier:@"9bZkp7q19f0"];
[self presentMoviePlayerViewControllerAnimated:videoPlayerViewController];

Answer 1

在foo超出范围之前，你正在检查内存泄漏，因此它没有机会调用它的析构函数，这反过来可能会清除所有LL_elements（假设，因为你还没有发布析构函数代码）。试试这样：

int main(int argc, const char * argv[]) {
    {
        Linkedlist foo; 
        foo.push_back(3);
        foo.push_back(5);
        foo.push_back(6);
        foo.push_back(7); 
    }
    _CrtDumpMemoryLeaks();
    return 0;
}

尽管析构函数调用，内存泄漏

1 个答案: