声明指向结构的指针后的值是什么

Question

例如，在我声明节点struct

之后

Proc

我知道它会自动将struct node { int data; node *next; } int main(){ node *root = new node; } 初始化为0，但root->data会发生什么。是初始化为nullptr还是什么？

Answer 1

Neither of those members will be initialized as it stands. If you want them to be set to their "default values" 0 and nullptr respectively, you can use something like this:

struct node {
    int data {};
    node *next {};
};

Now, in every new instance, you will have data == 0 and next == nullptr. This C++11 feature is called "default member initializer".

---

If you cannot use C++11, you can achieve this value initialization either via

node* root = new node();  // <- Note the parenthesis 

as @vsoftco pointed out or via aggregate initialization like this:

node root = {};

I would however prefer the variant at the top of this post if possible as it yields less opportunity for mistakes.