C# 4.0 Anonymous Functions

Question

How do I do the following shown in Javascript in C# 4.0:

var output = doSomething(variable, function() {
    // Anonymous function code
});

I'm sure I've seen this somewhere before but I cannot find any examples.

See [how-to-call-anonymous-function-in-c](http://stackoverflow.com/questions/3923864/how-to-call-anonymous-function-in-c) — nawfal, Jul 06 '14 at 12:57

score 5 · Answer 1 · answered Feb 17 '11 at 22:37

Using a lambda expression (parameterless, therefore empty parentheses), it is very simple:

var output = doSomething(variable, () => {
    // Anonymous function code
});

In C# 2.0, the syntax was a bit longer:

SomeType output = doSomething(variable, delegate {
    // Anonymous function code
});

Richard Marskell - Drackir · Accepted Answer · 2011-02-17T22:56:32.390

2

You'll want to look in to Lambda Expressions though it's not QUITE like JavaScript because C# works quite a bit differently. You may also want to check out delegates.

Example Code:

namespace Test {
    class Tests {
        delegate string MyDelegate();

        public void Main(string[] args) {
            var output = doSomething("test1", () => { return "test2";} );
        }

        public string doSomething(string test, MyDelegate d) {
            return test + d();
        }
    }
}

edited Feb 17 '11 at 22:56

answered Feb 17 '11 at 22:18

Richard Marskell - Drackir

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Could you please provide an example which does the same as outlined in the question? – GateKiller Feb 17 '11 at 22:19
@GateKiller: I added an example. – Richard Marskell - Drackir Feb 17 '11 at 22:41
I guess not as simple as JS but that's the best example I've seen on how to do the above. Thank you :) – GateKiller Feb 17 '11 at 23:12
@GateKiller: Yeah, it's C#'s strongly typed nature. It's not really meant to do stuff like that. Lambda Expressions make it a lot better but still that's probably about as simple as you're gonna get. – Richard Marskell - Drackir Feb 17 '11 at 23:15

score 2 · Answer 3 · answered Feb 17 '11 at 22:19

2

 var output = (x) => {
     // Anonymous function code
 };

answered Feb 17 '11 at 22:19

Kris Ivanov

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So does (x) equal doSomething() in my example? – GateKiller Feb 17 '11 at 22:20
`x` is the parameter of the anonymous function. – Richard Marskell - Drackir Feb 17 '11 at 22:22
I've quickly tested something like `(MessageBox.Show) => { return "Hello World"; }` but it throws an error. Could you please provide a full example so that I understand fully? – GateKiller Feb 17 '11 at 22:27
I'm getting the impression that I need to declare the delegate before I can use it. Is this correct? If so, doesn't that defeat the point of them? – GateKiller Feb 17 '11 at 22:30
what exactly are you trying do? differently from Java Script you need to tell what type x is when "it is difficult or impossible for the compiler to infer the input types" – Kris Ivanov Feb 17 '11 at 22:35

C# 4.0 Anonymous Functions

3 Answers3