C# List.Sort 与 lambda 表达式
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List.Sort with lambda expression
提问by user673679
I'm trying to sort part of a list with a lambda expression, but I get an error when trying to do so:
我正在尝试使用 lambda 表达式对列表的一部分进行排序，但是在尝试这样做时出现错误：
List<int> list = new List<int>();
list.Add(1);
list.Add(3);
list.Add(2);
list.Add(4);
// works fine
list.Sort((i1, i2) => i1.CompareTo(i2) );
// "Cannot convert lambda expression to type 'System.Collections.Generic.IComparer<int>' because it is not a delegate type"
list.Sort(1, 2, (i1, i2) => i1.CompareTo(i2) );
foreach (int i in list)
Console.WriteLine(i);
At a guess this is because there's no System.Comparison overload for the sort that takes a range. Is this omitted for any particular reason?
猜测这是因为对于采用范围的排序没有 System.Comparison 重载。是否出于任何特殊原因省略了这一点？
Is there an easy way of getting a suitable IComparer from the lambda expression (like a class I can just use to go list.Sort(1, 2, new CompareyThing<int>((...) => ...))or something)?
有没有一种简单的方法可以从 lambda 表达式中获取合适的 IComparer（比如一个我可以用来去的类list.Sort(1, 2, new CompareyThing<int>((...) => ...))）？
采纳答案by Lee
You can use the Comparer.Createmethod, although this appears to be new in .Net 4.5
您可以使用Comparer.Create方法，尽管这在 .Net 4.5 中似乎是新的
list.Sort(1, 2, Comparer<int>.Create((i1, i2) => i1.CompareTo(i2)));
You can always create your own comparer:
您始终可以创建自己的比较器：
public class FuncComparer<T> : IComparer<T>
{
private readonly Func<T, T, int> func;
public FuncComparer(Func<T, T, int> comparerFunc)
{
this.func = comparerFunc;
}
public int Compare(T x, T y)
{
return this.func(x, y);
}
}
Then your code would be:
那么你的代码将是：
list.Sort(1, 2, new FuncComparer<int>((i1, i2) => i1.CompareTo(i2)));
回答by Tim Schmelter
You could create a custom comparer if you're not using .Net 4.5:
如果您不使用 .Net 4.5，您可以创建一个自定义比较器：
class IntComparer : IComparer<int>
{
public int Compare(int x, int y)
{
return x.CompareTo(y);
}
}
list.Sort(1, 2, new IntComparer());
