C# 给出 CS0019 错误：运算符不能应用于类型 'T' 和 'T' 的操作数

Question

我试图将AVL树转换为通用，但我面临几个类型错误。

操作符不能用于'T'和'T'类型的操作数

private Node RecursiveInsert(Node current, Node n)
{
if (current == null)
{
current = n;
return current;
}
else if (n.data < current.data) // Gives Error        {
current.left = RecursiveInsert(current.left, n);
current = balance_tree(current);
}
else if (n.data > current.data) // Gives Error        {
current.right = RecursiveInsert(current.right, n);
current = balance_tree(current);
}
return current;
}

///

public class Node
{
public T data { get; set; }
public Node left { get; set; }
public Node right { get; set; }
public Node(T data)
{
this.data = data;
}
}
public Node root;

Answer 1

编辑:在我发布这篇文章之前，我设法剪掉了一个代码片段。

首先，Node类中的泛型类型需要实现iccomparable接口才能做到这一点。

public class Node<T> where T : ICompareable
{
public T data { get; set; }
public Node<T> left { get; set; }
public Node<T> right { get; set; }
public Node<T>(T data)
{
this.data = data;
}
}

其次，iccomparable不会重载'<'和'>'操作符。你需要这样做

else if (n.data.CompareTo(current.data) < 0) {
current.left = RecursiveInsert(current.left, n);
current = balance_tree(current);
}

Answer 2

您可以从Comparer<T>.Default获得通用比较器。

public class Node
{
public static readonly IComparer<T> comparer = Comparer<T>.Default;
}

然后你可以用它来比较泛型类型。

int c = Node.comparer.Compare(n.data, current.data);
if (c < 0) {
current.left = RecursiveInsert(current.left, n);
current = balance_tree(current);
}
else if (c > 0) {
current.right = RecursiveInsert(current.right, n);
current = balance_tree(current);
}