C# 这是遍历 .NET LinkedList 并删除元素的好方法吗？
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Is this a good way to iterate through a .NET LinkedList and remove elements?
提问by they changed my name
I'm thinking of doing the following:
我正在考虑执行以下操作：
for(LinkedListNode<MyClass> it = myCollection.First; it != null; it = it.Next)
{
if(it.Value.removalCondition == true)
it.Value = null;
}
What I'm wondering is: if simply pointing the it.Valueto null actually gets rid of it.
我想知道的是：如果简单地指向it.Valuenull 实际上摆脱它。
采纳答案by Oli
Surely (with a linked list) you need to change the link.
当然（使用链表）您需要更改链接。
Eg, if you want to remove B from the LL A-B-C, you need to change A's link to B to C.
例如，如果要从 LL ABC 中删除 B，则需要将 A 与 B 的链接更改为 C。
I'll admit I'm not familiar with the .NET implementation of linked lists but hopefully that's a start for you.
我承认我不熟悉链表的 .NET 实现，但希望这对您来说是一个开始。
回答by Vlad
You are changing the value pointed to by a LinkedListNode; beware that your list will contain a hole (emptynode) now.
您正在更改 a 指向的值LinkedListNode；请注意，您的列表现在将包含一个洞（空节点）。
Instead of A - B - Cyou are going to have A - null - C, if you "delete" B. Is that what you want to achieve?
而不是A - B - C你将要拥有A - null - C，如果你“删除” B。这就是你想要达到的目标吗？
回答by JDMX
I assume something like this is required
我认为需要这样的东西
for ( LinkedListNode<MyClass> it = myCollection.First; it != null; it = it.Next ) {
if ( it.Value.removalCondition == true ) {
if ( it.Previous != null && it.Next != null ) {
it.Next.Previous = it.Previous;
it.Previous.Next = it.Next;
} else if ( it.Previous != null )
it.Previous.Next = it.Next;
} else if ( it.Next != null )
it.Next.Previous = it.Previous;
it.Value = null;
}
}
回答by Mark Milbourne
If you can convert to using List<> rather than LinkedList<> then you can use the RemoveAll() operation. Pass an anonymous delegate like this;
如果您可以转换为使用 List<> 而不是 LinkedList<> 那么您可以使用 RemoveAll() 操作。像这样传递一个匿名委托；
List<string> list = new List<string>()
{
"Fred","Joe","John"
};
list.RemoveAll((string val) =>
{
return (0 == val.CompareTo("Fred"));
});
All this is using Linq extensions.
所有这些都是使用 Linq 扩展。
If you can't convert to using a list then you can use the ToList<>() method to convert it. But you'll then have to do some clear and insertion operations. Like this;
如果您不能转换为使用列表，那么您可以使用 ToList<>() 方法来转换它。但是您随后必须执行一些清除和插入操作。像这样;
LinkedList<string> str = new LinkedList<string>();
str.AddLast("Fred");
str.AddLast("Joe");
str.AddLast("John");
List<string> ls = str.ToList();
ls.RemoveAll((string val) => val.CompareTo("Fred") == 0);
str.Clear();
ls.ForEach((string val) => str.AddLast(val));
If all this still isn't palatable then try doing a copy of the LinkedList like this;
如果所有这些仍然不好吃，那么尝试像这样复制 LinkedList；
LinkedList<string> str = new LinkedList<string>();
str.AddLast("Fred");
str.AddLast("Joe");
str.AddLast("John");
LinkedList<string> strCopy = new LinkedList<string>(str);
str.Clear();
foreach (var val in strCopy)
{
if (0 != val.CompareTo("Fred"))
{
str.AddLast(val);
}
}
I hope that helps.
我希望这有帮助。
回答by Davit Tvildiani
As far as I understood You want to iterate in linkedlist with for cycle which olso contains null -s , so you can use folowing :
据我了解，您想使用 for 循环在链表中进行迭代，其中 olso 包含 null -s ，因此您可以使用以下内容：
for (LinkedListNode<string> node = a.First; node != a.Last.Next; node = node.Next)
{
// do something here
}
回答by ILIA BROUDNO
Setting the it.Value to null will not remove the node from the list Here is one way:
将 it.Value 设置为 null 不会从列表中删除节点这是一种方法：
for(LinkedListNode<MyClass> it = myCollection.First; it != null; )
{
LinkedListNode<MyClass> next = it.Next;
if(it.Value.removalCondition == true)
myCollection.Remove(it); // as a side effect it.Next == null
it = next;
}
