问题描述
我正在提示用户输入，直到输入的值为-1.输入-1时，列表将按排序顺序打印出来.但是，该程序不能那样工作.理想的运行就像这样....
I am prompting user input until the value entered is -1. When a -1 is entered, the list prints out in sorted order. However, the program doesn't work like that. An ideal run goes like this....
输入:4 3 2 -1
Input: 4 3 2 -1
输出:2 3 4
我的输出:3 4带有"NullReferenceException"错误出现在" Console.WriteLine(cur.number);"
My Output: 3 4 with a "NullReferenceException" error at "Console.WriteLine(cur.number);"
这是我的代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace LinkedListlab
{
public class LinkedList
{
public class Node
{
public Node link;
public int number { get; set; }
public Node(int num)
{
this.number = num;
}
}
private Node Head;
public int count = 0;
//adds new node to list
public void AddNewNode(int input)
{
if (input != -1)
{
this.count++;
Node ToAdd = new Node(input);
ToAdd.number = input;
if (count == 1)
{
ToAdd.link = null;
Head = ToAdd;
return;
}
if (input < Head.number)
{
ToAdd.link = Head;
Head = ToAdd;
}
else
{
Node current = Head;
Node prior = Head;
while (current != null)
{
if (input < current.number)
{
break;
}
prior = current;
current = current.link;
}
ToAdd.link = current;
prior.link = ToAdd;
}
}
}
//prints nodes
public void PrintAll()
{
Node cur;
cur = this.Head;
Console.WriteLine("Output:");
while (cur != null)
{
cur = cur.link;
Console.WriteLine(cur.number);
}
}
}
class Program
{
static void Main(string[] args)
{
LinkedList list = new LinkedList();
int input;
do
{
Console.WriteLine("Enter an integer, or -1 to exit the program...");
input= Convert.ToInt32(Console.ReadLine());
list.AddNewNode(input);
}
while (input != -1);
list.PrintAll();
Console.Read();
}
}
}
推荐答案
输入:4 3 2 -1
Input: 4 3 2 -1
输出:2 3 4
我的输出:3 4带有"NullReferenceException"错误出现在" Console.WriteLine(cur.number);"
My Output: 3 4 with a "NullReferenceException" error at "Console.WriteLine(cur.number);"
Console.WriteLine("Output:");
while (cur != null)
{
cur = cur.link;
Console.WriteLine(cur.number);
}
}
}
如果您在此处更改订单会怎样?
What happens if you change the order here?
while (cur != null)
{
//cur = cur.link;
Console.WriteLine(cur.number);
cur = cur.link; // <<<<
}
-韦恩
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