C语言 释放它的所有内存，并设置它的头指针为NULL(空列表)

Question

我在考试中遇到了一个问题。

编写一个函数DeleteList()，它获取一个列表，释放它的所有内存并设置它的head指针指向NULL(空列表)。

解为

void DeleteList(struct node** headRef) {
    struct node* current = *headRef;
    struct node* next;
    while (current != NULL) {
        next = current->next; 
        free(current); 
        current = next; 
    }
    *headRef = NULL;
}

我的解决方案:

void DeleteList(struct node** headRef) {
    struct node* current = *headRef;
    while (current != NULL) {
        *headRef = *headRef->next;
         free(current);
         current = * headRef;
    }
    free(current);
    *headRef = NULL;
}

这个方法正确吗?谢谢你,

Answer 1

您的解决方案不会这样做"并将其头部指针设置为NULL"，因为您的建议(*headRef = NULL;)的最后一行不再将传入的headRef值设置为NULL，而是将列表中的最终Next点(已经为NULL)

Answer 2

free(current); //you should remove this line after the while loop because when while loop breaks the current is already NULL so free(NULL) makes no sense. 
*headRef = NULL;

看这里Free(NULL).

Answer 3

void DeleteList(struct node **headRef)
{
    struct node *current = *headRef;
    while (current) {
         *headRef = (*headRef)->next;
         free(current);
         current = *headRef;
    }
    *headRef = NULL;
}