How to use pointers to objects in C++

In C++, you can create a pointer to an object, that is, a secondary pointer, which is used to handle complex data structures and indirect reference objects. The specific steps are as follows: Define a secondary pointer of type T**, where T is the object type. Get the address of the pointer ptr pointing to the object through &ptr and assign it to the secondary pointer. Use double dereference *currPtrPtr to access the object. When accessing the object data, you need to dereference the secondary pointer first.

Usage of pointer to object in C++

C++ allows creation of pointer to object, i.e. secondary pointer. This provides flexibility for handling complex data structures and indirectly referenced objects.

Syntax:

// 指向对象的二级指针
T** ptrPtr = &ptr;

Where:

• T is the object type
• ptr is a pointer to an object

Practical case:

Suppose we have a Node class, which represents a linked list Node:

class Node {
public:
    int data;
    Node* next;
};

We can use the secondary pointer to traverse the linked list:

Node* head = new Node;
head->data = 1;
head->next = new Node;
head->next->data = 2;

// 二级指针
Node** currPtrPtr = &head;

// 只要二级指针不为 nullptr，就继续遍历
while (*currPtrPtr != nullptr) {
    // 通过二级指针访问对象
    cout << (*currPtrPtr)->data << " "; // 输出节点数据

    // 将二级指针前进一位
    currPtrPtr = &(*currPtrPtr)->next;
}

Other notes:

• The secondary pointer is A pointer to a pointer, which can point to a nullptr or to a pointer to an object.
• When accessing an object, you need to dereference the secondary pointer before you can access the object pointed to by the pointer.
• The type of the secondary pointer should match the type of the pointer it points to.

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