函数内部的抽象类对象指针调用的C ++ abort（）

Question

I've got an abstract class pendulum with pure virtual function period() and two descendants(math and spring) implementing function period().

I've got a pendulum **pendArray = new pendulum*[n]. I fill the array with math and spring class object pointers and pass the array to the findMaxPeriod(pendulum **a) function:

void findMaxPeriod(pendulum **a) 
{
    pendulum *maxPend = new math();
    double maxPeriod = 0;
    double period1;
    for (int i = 0; i < n; i++)
    {
        pendulum *pend = a[i];
        period1 = pend->period();
        if (period1 > maxPeriod)
        {
            maxPend = a[i];
        }
    }
    cout << "max period pendulum is " << maxPend << ". It's period is " << maxPend->period();
}

It crashes on the

period1 = pend->period();

with "debug error! abort() has been called"

What am I doing wrong? Here is all my code: https://hello-site.ru/share/Abort-called-problem/ Thanks in advance.

Answer 1

The problem is here:

math pendM;
cin >> pendM;
pendArray[i] = &pendM;

In the third line, you've place a pointer-to- pendM into your array, but pendM gets destroyed immediately after that line, when it goes out of scope. If you want to keep it around (and thus avoid a dangling pointer in your pendArray ) you'll need to allocate it from the heap instead of on the stack.

Same thing goes for pendS in the next block below that.