为什么这个非常简单的小 C++ 程序以 -1073741819 (0xC0000005) 终止？

Question

I have a simple class with a destructor. If I instantiate an object from it with default constructor, then the program terminates succesfully, but if I instantiate it with a constructor that has any parameter, it terminates unsuccesfully.

#include <iostream>
#include <list>

class MyClass {
public:
    std::list<int>* myList;
    MyClass();
    MyClass(int a);
    ~MyClass();
};

MyClass::MyClass() {}
MyClass::MyClass(int a) {}
MyClass::~MyClass() { delete myList; }

int main()
{

    // If I do only this, the program terminates succesfully with 0 as return value
    MyClass graph1();

    // But if I do this, the program terminates unsuccesfully
    MyClass graph2(3);

    return 0;
}

Answer 1

MyClass graph1(); doesn't create an instance of MyClass , whether initialized with the default constructor or otherwise. Rather, it's a declaration of a function taking no parameters and returning MyClass . See also: most vexing parse

MyClass graph2(3); does create an instance of MyClass . Its constructor leaves myList pointer uninitialized, and then its destructor exhibits undefined behavior by way of accessing said uninitialized pointer.