普通情況的結點交換

					temp_pre->next = p;
					p_pre->next = p->next;//key step 
					p->next = temp->next;
					temp->next = p_pre->next;
					p_pre->next = temp;

交換結點時一定要注意那個相鄰結點的情況，不然……

----相鄰結點使用一般情況

會出現大錯誤

相鄰結點單獨處理

					temp->next = p->next;
					p->next = temp;
					temp_pre->next = p;
 

具體程式碼如下（整體是一個選擇排序的演算法）

void sort_dec(book* head)
{
	book* temp_pre=head;
	book* p_pre = head;
	book* ex;
	//選擇排序
	for (book* temp = head->next; temp != NULL; temp = temp->next)
	{
		p_pre = temp;
		for (book* p = temp->next; p != NULL; p = p->next)
		{
			if (temp->price < p->price)
 

			{
				//下面的修改指標的交換方式
				if (temp->next == p)      //temp與p為相鄰結點
				{
					temp->next = p->next;
					p->next = temp;
					temp_pre->next = p;
				}
				else                    //一般情況
				{
					temp_pre->next = p;
					p_pre->next = p->next;//key step 
					p->next = temp->
 
next;
					temp->next = p_pre->next;
					p_pre->next = temp;
				}

				ex = temp;
				temp = p;
				p = temp;
			}
			p_pre = p;
		}
		temp_pre = temp;
	}
}