class p {
public string Name { get; set; }
public int Age { get; set; }
};
static List<p> ll = new List<p>
{
new p{Name="Jabc",Age=53},new p{Name="Mdef",Age=20},
new p{Name="Exab",Age=45},new p{Name="G123",Age=19}
};
protected static void SortList()
{
IComparer<p> mycomp = (x, y) => x.Name.CompareTo(y.Name); <==(Line 1)
ll.Sort((x, y) => x.Name.CompareTo(y.Name));<==(Line 2)
}
Here the List.sort expects an IComparer<p>
as parameter. And it works with the lambda
as shown in Line 2. But when I try to do as in Line 1, I get this error:
Cannot convert lambda expression to type System.Collections.Generic.IComparer' because it is not a delegate type
I investigated this for quite some time but I still don't understand it.Maybe my understanding of IComparer is not quite good.Can somebody give me a hand ?
When you do ll.Sort((x, y) => x.Name.CompareTo(y.Name));
it uses the overload for Comparison<T>
, not IComparer
. Comparison<T>
is a delegate, so you can use a lambda expression for it.
Comparison<p> mycomp = (x, y) => x.Name.CompareTo(y.Name);
will work.
There's an existing solution you might refer to: https://stackoverflow.com/a/16839559/371531
This one uses Comparer<T>.Create introduced in .NET Framework 4.5.
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