c - 带指针的无限循环 - 为什么？

Question

我对 C 和指针比较陌生。我正在尝试排序然后打印结构的链接列表。要么我遗漏了逻辑错误，要么我没有完全理解指针。有人可以向我解释一下这段代码中缺少什么吗？预先感谢您!

// *** Sort Linked List ( Merge Sort ) ***

struct address_node *newRoot;

// ptr, rearPtr, and tempRoot are also struct Pointers
newRoot = root;
root = root->next;

while (root != NULL)
{
    tempRoot = root;
    ptr = newRoot;
    rearPtr = newRoot;

    while (ptr != NULL)
    {
        printf("here");
        if ((root->frequency) == (ptr->frequency))
        {                       // SPECIAL CASE: To determine read hierarchy for repeated
                                // Entries
            if ((root->read_order) < (ptr->read_order))
            {
                if (ptr == newRoot)
                {
                    root = root->next;
                    tempRoot->next = newRoot;
                    newRoot = tempRoot;
                    ptr = NULL;
                }
                else
                {
                    root = root->next;
                    tempRoot->next = ptr;
                    rearPtr->next = tempRoot;
                    ptr = NULL;
                }
            }
        }
        else if ((root->frequency) > ptr->frequency)
        {                       // To ADD BEFORE an ENTRY
            if (ptr == newRoot)
            {
                root = root->next;
                tempRoot->next = newRoot;
                newRoot = tempRoot;
                ptr = NULL;
            }
            else
            {
                root = root->next;
                tempRoot->next = ptr;
                rearPtr->next = tempRoot;
                ptr = NULL;
            }
        }
        else if (ptr->next == NULL)
        {                       // if END OF LIST
            root = root->next;
            ptr->next = tempRoot;
            ptr = NULL;
        }
        else
        {                       // SPOT NOT FOUND YET< MOVE FORWARD THROUGH LIST
            rearPtr = ptr;
            ptr = ptr->next;
        }
    }
}

// *** PRINT ***
ptr = newRoot;
if (numOut == 0)
{
    while (ptr != NULL)
    {
        printf("0x%zx :%d\n", ptr->address, ptr->frequency);
        ptr = ptr->next;
    }
}
else
{
    while (ptr != NULL && numOut > 0)
    {
        printf("0x%zx :%d\n", ptr->address, ptr->frequency);
        numOut--;
        ptr = ptr->next;
    }
}

Answer 1

你所有的指针似乎都指向同一个东西，root。因此，在一种情况下，root 会向前移动，但随后您将 root->next 指向 root 后面的内容。因此，想象 root 指向 bob，而 root->next 指向 bill，假设你的第一个 if 嵌套都为 true，root = bill 但 root->next = bob。没有任何进展。