foo.cc: In member function ‘void IntLinkList::InsertAt(int, int)’:
foo.cc:107:39: error: ‘i’ was not declared in this scope
  107 |                         nnode->next = i;
      |                                       ^
foo.cc:111:21: error: ‘i’ was not declared in this scope
  111 |                 if (i->next == NULL)//如果要插入尾结点
      |                     ^
foo.cc:116:31: error: ‘i’ was not declared in this scope
  116 |                 nnode->next = i->next;//链接插入的结点和k号结点
      |                               ^
foo.cc: In function ‘int main(int, char**)’:
foo.cc:136:14: error: ‘i’ was not declared in this scope
  136 |         for (i = 0; i < n; i++)
      |              ^