下面这段代码对象在析构的时候判断了指针是否为空再进行操作,为何还会出现double free 的问题?
#include<iostream>
using namespace std;
class base {
public:
base(int *a):p(a) {}
base(int num) :p(new int(num)) {}
base(base& mid) :p(mid.p) {
cout << "base is constructing!\n";
if (p != NULL) cout << "p is not NULL!\n";
}
~base() {
if (p != NULL ) {
delete p;
p = NULL;
}
if (p == NULL)
cout << "p is NULL!\n";
}
private:
int *p;
};
int main() {
base one(1);
base two(one);
}