指向C++指针的指针

Question

在这个程序中，为什么我不能使用* head = * head-> next在更改头部行？

这是一个geeksforgeek算法...

或请建议我一些很好的教程来学习指针

void deleteNode(struct node **head_ref, int key) 
{ 
    // Store head node 
    struct node* temp = *head_ref, *prev; 

    // If head node itself holds the key to be deleted 
    if (temp != NULL && temp->data == key) 
    { 
     *head_ref = temp->next; // Changed head 
     free(temp);    // free old head 
     return; 
    } 

    // Search for the key to be deleted, keep track of the 
    // previous node as we need to change 'prev->next' 
    while (temp != NULL && temp->data != key) 
    { 
     prev = temp; 
     temp = temp->next; 
    } 

    // If key was not present in linked list 
    if (temp == NULL) return; 

    // Unlink the node from linked list 
    prev->next = temp->next; 

    free(temp); // Free memory 
} 

Answer 1

您可以使用*head_ref = *head_ref->next。

但使用temp只是为了保持清楚。如果您使用temp->data进行比较，然后使用*head_ref进行删除，则看起来有点模糊。

如果您确实想使用*head_ref，那么您可以更改代码以使其看起来更清晰。像，

// If head node itself holds the key to be deleted 
if (*head_ref != NULL && *head_ref->data == key) 
{ 
    *head_ref = *head_ref->next; // Changed head 
    free(temp);     // free old head 
    return; 
}