二叉排序树删除某个结点 这样做哪里错了？刚开始学不太懂

请问删除的代码是不是不对呀，用一个指针指向要删除的节点后再改变他的值对原来的树没影响吧？
那我如果想用 那个 search函数的话 应该怎么写呢 还是必须直接用T开始找呀 就像最下面的代码一样

#include<stdio.h>
#include<stdlib.h>

typedef int KeyType;
typedef struct BSTNode {
    KeyType key;
    struct BSTNode* lchild;
    struct BSTNode* rchild;
}BSTNode,*BiTree;
//54,20,66,40,28,79,58
int BST_Insert(BiTree& T, KeyType k)
{
    if (NULL == T)
    {
        T = (BiTree)malloc(sizeof(BSTNode));//为新结点申请空间
        T->key = k;
        T->lchild = NULL;
        T->rchild = NULL;
        return 1;
    }
    if (k == T->key) 
        return 0;//相同元素不插入
    else if (k < T->key) 
        return BST_Insert(T->lchild, k);
    else 
        return BST_Insert(T->rchild, k);
}
void Create_BST(BiTree& T, KeyType str[], int n)
{
    T = NULL;
    for (int i = 0; i < n; i++)
    {
        BST_Insert(T, str[i]);
    }
}
void Inorder(BiTree T)
{
    if(T != NULL)//注意不要用while
    {
        Inorder(T->lchild);
        printf("%3d", T->key);
        Inorder(T->rchild);
    }
}
BSTNode* BST_Search(BiTree T, KeyType key, BiTree& p)
{
    p = NULL;
    while (NULL != T && key != T->key)
    {
        p = T;
        if (key > T->key) T = T->rchild;//比当前节点大，去右边找
        else T = T->lchild;//比当前节点小，去左边找
    }
    return T;
}
void DeleteNode(BiTree& T, KeyType x)
{
    BiTree p;
    BiTree del = BST_Search(T, x, p);
    if (del == NULL) return;
    if (del->lchild == NULL)
    {
        BiTree temp = del;
        del = del->rchild;
        free(temp);
    }
    else if (del->rchild == NULL)
    {
        BiTree temp = del;
        del = del->lchild;
        free(temp);
    }
    else
    {
        BiTree dead = del->lchild;
        while (NULL != dead->rchild) dead = dead->rchild;
        del->key = dead->key;
        DeleteNode(del->lchild, dead->key);
    }

}
int main()
{
    BiTree search;
    BiTree parent;//存储父亲结点的地址值
    BiTree T;
    KeyType str[]= { 54,20,66,40,28,79,58 };//将要进入二叉排序树的元素值
    Create_BST(T, str, 7);
    Inorder(T);
    printf("\n");
    search = BST_Search(T, 40, parent);
    if (search)
    {
        printf("找到对应结点，值=%d\n", search->key);
    }
    else {
        printf("未找到对应结点\n");
    }
    DeleteNode(T,54);
    Inorder(T);
    printf("\n");
}

就像这样

void DeleteNode(BiTree& T, KeyType x)
{
    BiTree p;
    BiTree del = BST_Search(T, x, p);
    if (del == NULL) return;
    if (del->lchild == NULL)
    {
        BiTree temp = del;
        del = del->rchild;
        free(temp);
    }
    else if (del->rchild == NULL)
    {
        BiTree temp = del;
        del = del->lchild;
        free(temp);
    }
    else
    {
        BiTree dead = del->lchild;
        while (NULL != dead->rchild) dead = dead->rchild;
        del->key = dead->key;
        DeleteNode(del->lchild, dead->key);
    }

}