How to return a value from lambda function

Question

I have this code and it's work correctly,

    private void button1_Click(object sender, EventArgs e)
    {
        var func = new Action<int, int>((a, b) =>
        {
            var sum = a + b;
            MessageBox.Show(sum.ToString());
            //How can I return sum?
        });

        //var result=func(2,3);
        func(2, 3);
    }

How I can change func to return sum variable, I want use function as:

   var result=func(2,3);

Can u explain the relation of your subject and your question?! — HaMeD
– HaMeD, Commented Mar 8, 2014 at 19:39
Sounds like you want Func<int, int, int> which you can return a+b from — Charleh
– Charleh, Commented Mar 8, 2014 at 19:40
@Charleh sorry for wrong title, if you vote down me please vote me up. — Hadi Sharifi
– Hadi Sharifi, Commented Mar 8, 2014 at 19:53

nemesv · Accepted Answer · 2014-03-08 19:41:12Z

4

An Action represents a method which does not return a value.

If you want to return a value you need to use a Func<TResult> which encapsulates a method that returns a value of the type specified by the TResult parameter.

So in your case you need a Func<T1, T2, TResult> where the arguments are int and so does the return type:

var func = new Func<int, int, int>((a, b) =>
{
    var sum = a + b;
    MessageBox.Show(sum.ToString());
    return sum;
});

var result=func(2,3);

answered Mar 8, 2014 at 19:41

nemesv

140k16 gold badges424 silver badges364 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jeppe Stig Nielsen Over a year ago

Not related to the question, but you don't need the new syntax when you create a delegate from a lambda, so either Func<int, int, int> func = (a, b) => { var sum = a + b; MessageBox.Show(sum.ToString()); return sum; }; or var func = (Func<int, int, int>)((a, b) => { var sum = a + b; MessageBox.Show(sum.ToString()); return sum; }); will give the same.

Collectives™ on Stack Overflow

How to return a value from lambda function

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related