指针改变它指向的地址的值

Question

I would expect pFirst to always point to the same place in the address. However it looks like pFirst moves along with pCurrent even though the function only entered the Else statement once.

void Push(T data) {
    ++_size;
    Data d = Data(data);
    if (_pCurrent != nullptr) _pCurrent->SetNext(&d);
    else _pFirst = &d;

    _pCurrent = &d;
}

Answer 1

d is created locally so it does not exist after the function is over, Debug error is a littl bit strange,because the program initializes a new element at the same address so I did not immediately understand exactly what is happening. This is working version:

void Push(T data) {
        ++_size;
        Data*d = new Data(data);
        if (_pCurrent != nullptr)
            _pCurrent->_pNext = d;
        else
            _pFirst = d;
           _pCurrent = d;
    }

Answer 2

Data should be a static variable, the code should be like this:

Data d;
void UpdateData(Data newData) {
    //Do something on d using newData;
}

void Push(T data) {
        ++_size;
        UpdateData(data);
        if (_pCurrent != nullptr)
            _pCurrent->_pNext = d;
        else
            _pFirst = d;
           _pCurrent = d;
    }