I am trying to replace following statement with the lambda expression:
List<ABC> l = new List<ABC>();
l.Find(delegate(ABC a) { return a.A == 4; });
I tried
l.Find((ABC a)=>a.A==4;);
but that is obviously incorrect. Thanks
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4 Answers
Just to be complete, any of these would be valid:
// Fullest version
l.Find((ABC a) => { return a.A==4; });
// Infer the type of the parameter
l.Find((a) => { return a.A==4; });
// Single parameter - can remove the ()
l.Find(a => { return a.A==4; });
// Single expression - can remove braces and semi-colon
l.Find(a => a.A == 4);
(You can use the "single expression" part independently of the other shortcuts.)
Comments
Firstly, note that it is still a delegate - simply: rather, it uses the lambda syntax rather than the anonymous method syntax (it essentially means exactly the same thing, though).
As for how to fix it: just take away the ;:
l.Find((ABC a) => a.A == 4);
or more simply:
l.Find(a => a.A == 4);
(brackets are only necessary if you have multiple parameters; explicit types are useful for disambiguation)
Comments
Why do you not use it in simple way, I think there is no need to write (ABC a):
l.Find(a => a.A == 4);
This statement l.Find((a) => a.A == 4); can be written as your statement l.Find(delegate(ABC a) { return a.A == 4; });. As you seen predicate can be replaced with the anonymous method( delegate ).
(.NET 2.0)
fooList.Find(delegate (Foo f) { return f.Equals(fooTarget); });
or (later version)
fooList.Find(f => f.Equals(fooTarget));
