Return 用户定义结构到动态数组元素

Question

我正在尝试创建一个动态数组来在数组的每个元素中存储一个链表。所以我定义链表结构如下：

//data type for adjacent bus stop
typedef struct AdjStopNode
{
    int distance; //travel distance from the bus original stop to this adjcent stop
    int stopID;
    struct AdjStopNode *prev; //pointer to previous bus stop
    struct AdjStopNode *next; //pointer to next bus stop
} AdjStopNode;

AdjStopNode *newAdjStopNode(int distance, int stopID)
{
    AdjStopNode *newNode = (AdjStopNode *)malloc(sizeof(AdjStopNode));
    assert(newNode != NULL);
    newNode->distance = distance;
    newNode->stopID = stopID;
    newNode->next = NULL;
    return newNode;
}

typedef struct AdjStopList
{
    char stopname[20]; 
    int numOfAdjStp;   
    struct BusAtStopList *buslist;  
    struct AdjStopNode *first; //pointed at the first AdjBusStop of the linked list
    struct AdjStopNode *last;  //pointed at the first AdjBusStop of the linked list
} AdjStopList;

AdjStopList *newAdjStopList()
{
    AdjStopList *newList = (AdjStopList *)malloc(sizeof(AdjStopList));
    newList->buslist = newBusAtStopList();
    assert(newList != NULL);
    memset(newList, NULL, 20 * sizeof(newList[0]));
    newList->first = NULL;
    newList->last = NULL;
    newList->numOfAdjStp = 0;
    return newList;
}

然后我定义了一个动态数组来存储每个AdjStopList作为数组的一个元素如下：

typedef struct BusNetwork
{
    int nBusStop; //number of bus stops in the newwork
    struct AdjStopList *array;
} BusNetwork;

我为数组的每个元素分配一个空 AdjStopList 的函数如下：

//n is the number of AdjStopList
void listToArray(int n)
{
    BusNetwork *newBN;
    newBN = malloc(sizeof(BusNetwork));
    assert(newBN != NULL);
    newBN->nBusStop = n;
    newBN->array = malloc(n * sizeof(AdjStopList)); //create an array of n number of dejacency lists
    for (int i = 0; i < n; i++)
    {
        newBN->array[i] = newAdjStopList();
    }
}

上面的代码在 newBN->array[i] = newAdjStopList() 处给我的错误是

a value of type "AdjStopList *" cannot be assigned to an 
entity of type "struct AdjStopList" C/C++(513)

使用 VScode.

有人可以帮我解决这个问题并向我解释原因吗？非常感谢。

Answer 1

newBN->array 的类型是 struct AdjStopList * 所以 newBN->array[i] 的类型是 struct AdjStopList 但 newAdjStopList() 的 return 类型是 struct AdjStopList*。因此，这应该可以解释您在

行中将 struct AdjStopList* 分配给 struct AdjStopList 时看到的错误

newBN->array[i] = newAdjStopList();

我相信你应该改变

typedef struct BusNetwork
{
    int nBusStop; //number of bus stops in the newwork
    struct AdjStopList *array;
} BusNetwork;

到

typedef struct BusNetwork
{
    int nBusStop; //number of bus stops in the newwork
    struct AdjStopList **array;
} BusNetwork;

因此 array 成为指向 struct AdjStopList 的指针的数组。那么原始作业应该可以工作。

Return 用户定义结构到动态数组元素

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