数据结构 二叉树定义问题

btree *insert_node(btree *root,int node)
{
    btree *newpointer;
    btree *currentpointer;
    btree *parentpointer;
    newpointer=(btree*)malloc(sizeof(btree));
    newpointer->data=node;
    newpointer->lchild=NULL;
    newpointer->rchild=NULL;
    if(root==NULL)
    {
        return newpointer;
    }
    else
    {
        currentpointer=root;
        while(currentpointer!=NULL)
        {
            parentpointer=currentpointer;
            if(currentpointer->data>node)
            {
                currentpointer=currentpointer->lchild;
            }
            else
            {
                currentpointer=currentpointer->rchild;
            }
        }
        if(parentpointer->data>node)
        {
            parentpointer->lchild=newpointer;
        }
        else
        {
            parentpointer->rchild=newpointer;
        }
        return root;
    }
}
btree *create_btree(int data[],int len)
{
    int i;
    btree *root=NULL;
    for(i=0;i<len;i++)
    {
        root=insert_node(root,data[i]);
    }
    return root;
}
显示  处未处理的异常: 0xC0000005:
Bitree.exe 中的 0x00414c5e 处最可能的异常: 0xC0000005: 读取位置 0xccccccd0 时发生访问冲突
Bitree.exe 中的 0x00414c5e 处未处理的异常: 0xC0000005: 读取位置 0xccccccd0 时发生访问冲突
程序“[4012] Bitree.exe: 本机”已退出，返回值为 0 (0x0)。