C++单链表中删除指定范围内的元素

//删除指定范围内的所有元素
template<typename T>
void chain<T>::removeRange(int fromIndex, int toIndex)
{
chainNode<T>*deleteNode;
chainNode<T>*p = firstNode;
if (fromIndex == 0)                                //方法复杂度O(toIndex-fromIndex+1)
{                                                   //思想是如果首位是0号元素，则先删除0后面的元素，最后把0号元素删除
for (int i = 0; i < toIndex - fromIndex; i++)
{
deleteNode = p->next;
p->next = p->next->next;
delete deleteNode;
listSize--;
}
deleteNode = firstNode;
firstNode = firstNode->next;
delete deleteNode;
listSize--;
}
else                                             //如果是非0开始，则先找到起始元素的前驱，再逐个删除
{
for (int i = 0; i < fromIndex - 1;i++)
p = p->next;
for (int i = 0; i < toIndex - fromIndex + 1;i++)
{
deleteNode = p->next;
p->next = p->next->next;
delete deleteNode;
listSize--;
}
}
}