C 循环链表

Question

您好，我最近刚刚在 Java 中实现了一个循环链表，但我在使用 (C) 编程语言时遇到了一些麻烦 - 没有任何条目会打印到控制台。有人可以帮我处理循环链表的插入和输出部分吗？

这是插入函数以及输出函数。

/**
 *  FUNCTION        :   addWeapon
 *  DESCRIPTION     :   This function will add a new weapon to the weapon wheel.
 *  PARAMETERS      :   pWeaponHead
 *  RETURNS         :   true, false
 */
const bool addWeapon(struct Weapon* pWeaponHead, struct Weapon* pWeaponTail)
{
    struct Weapon* pNewWeapon = NULL;
    pNewWeapon = (struct Weapon*)malloc(sizeof(struct Weapon));

    // Check the system for sufficient memory.
    if (pNewWeapon == NULL) { return false; }
    else
    {
        // We have memory for a new weapon entry.
        getchar();
        printf(KPROMPTFORWEAPON);
        fgets(pNewWeapon->arsWeapon, K100BYTES, stdin);
        newLineRemover(pNewWeapon->arsWeapon);
        pNewWeapon->pNext = pNewWeapon;

        // Is the weapon wheel empty ?
        if (pWeaponHead == NULL) 
        {
            pWeaponHead = pNewWeapon;
            pWeaponTail = pNewWeapon;
            return true;
        }
        pWeaponTail->pNext = pWeaponHead;
        pNewWeapon->pNext = pNewWeapon;
        pWeaponHead = pNewWeapon;
    }
    return true;
}

/**
 *  FUNCTION        :   showWeaponWheel
 *  DESCRIPTION     :   This function will display the weapon selection
 *                      which is represented by the "Weapon Wheel" this allows
 *                      us to choose which weapon we would like that exists in the list.
 *  PARAMETERS      :   pWeaponHead
 *  RETURNS         :   true, false
 */
const bool showWeaponWheel(struct Weapon* pWeaponHead)
{
    // Check to see if the list is empty.
    if (pWeaponHead == NULL) { return false; }

    struct Weapon* pHead = pWeaponHead;
    printf("** -- Weapon Wheel -- \n");
    do
    {   
        printf("\t%s\n", pHead->arsWeapon);
        pHead = pHead->pNext;
    } while (pHead != pWeaponHead);
    return true;
}

Answer 1

好像有2个问题... 首先，如评论中所述，您已经传递了指针的值并试图更改它，但不会更改实际指针的值。您需要将该指针的地址作为双指针传递。这将帮助您添加第一个条目。其次，不懂

        pWeaponTail->pNext = pWeaponHead;
        pNewWeapon->pNext = pNewWeapon;
        pWeaponHead = pNewWeapon;

它只是将列表的尾部链接到列表的头部，并将新条目的尾部链接到它自己。这是行不通的

试试这个：

const bool addWeapon(struct Weapon** pWeaponHead, struct Weapon** pWeaponTail)
{
    struct Weapon* pNewWeapon = NULL;
    pNewWeapon = (struct Weapon*)malloc(sizeof(struct Weapon));

    // Check the system for sufficient memory.
    if (pNewWeapon == NULL) { return false; }
    else
    {
        // We have memory for a new weapon entry.
        getchar();
        printf(KPROMPTFORWEAPON);
        fgets(pNewWeapon->arsWeapon, K100BYTES, stdin);
        newLineRemover(pNewWeapon->arsWeapon);
        pNewWeapon->pNext = pNewWeapon;

        // Is the weapon wheel empty ?
        if (*pWeaponHead == NULL) 
        {
           *pWeaponHead = pNewWeapon;
           *pWeaponTail = pNewWeapon;
            return true;
        }
        (*pWeaponTail)->pNext = pNewWeapon;
        pNewWeapon->pNext = *pWeaponHead;
        *pWeaponHead = pNewWeapon;
    }
    return true;
}

C 循环链表

C Circular Linked list

c

circular-list