c或c++中树创建的结构对象变量点运算符和箭头运算符之间的差异[重复]

我必须澄清一个疑问,它在c和c++中也有相同的概念。

假设我有一个这样的结构:

struct Huffman
{
    int value;
    unsigned char sym;                 /* symbol */
    struct Huffman *left,*right;    /* left and right subtrees */
};

typedef struct Huffman Node;
Node * tree;

现在我使用树变量创建树。然后同时使用点运算符和箭头运算符。 这样地。

Arrorw运算符:

 for (i = 0; i < data_size; i++) 
    {
         // the problem is here this tree pointer don't store the values for all alphabets, it just remembers the last executed alphabet after this for loop.
        tree -> left = NULL;
        tree  ->right = NULL;
        tree -> symbol = storesym[i];
        tree  -> freq = storefreq[i];
        tree -> flag = 0;
        tree -> next = i + 1;
        cout<<"check1 : "<<tree -> symbol<<endl;
    } 

点运算符:

for (i = 0; i < data_size; i++) 
{
    tree[i].symbol = storesym[i];
    tree[i].freq = storefreq[i];
    tree[i].flag = 0;
    tree[i].left = tree[i].right = tree[i].value = NULL;
    tree[i].next = i + 1;
}

现在我无法理解 (1) 两者之间有什么区别? (2) 它们在内存中是如何分配的?