Perform action based on if statement using lambda

Question

How to write a fancy if statement in one line using lambda?

I want to have something like this:

this.SomeBoolValue == false ? (() => MessageBox.Show("False!")) : (() => MessageBox.Show("True!"));

Thanks

Follow up question: why lambda, there is no need here at all? — DavidG, Nov 27 '14 at 21:58
can do it without lambda, more curios about one line if statement. — inside, Nov 27 '14 at 21:59
Can still do an `if` on a single line, but it's harder to read. — DavidG, Nov 27 '14 at 22:01
@Ani - it looks like answer you've found solves exactly the same issue - closing as duplicate. — Alexei Levenkov, Nov 27 '14 at 22:05

score 2 · Accepted Answer · answered Nov 27 '14 at 22:04

It's really stupid and you should not do that! But for teaching purposes, here's code that does what you want.

(this.SomeBoolValue == false
    ? (Action)(() => MessageBox.Show("False!"))
    : (Action)(() => MessageBox.Show("True!")))();

You need to cast your lambda to some delegate type (here it's Action), because lambda expressions are typeless by default - they are typed according to the context.
You need to actually call the lambda, that's why there is () at the end.

Dunno why someone is downvoting, this is correct. Anyway, I'll give you a +1 — DavidG, Nov 27 '14 at 22:07

score 0 · Answer 2 · answered Nov 27 '14 at 22:03

Some 'single line' variants without using lambda that all achieve the same thing:

if(this.SomeBoolValue == false) MessageBox.Show("False!"); else MessageBox.Show("True!");

MessageBox.Show(this.SomeBoolValue ? "True!" : "False!");

MessageBox.Show(string.Format("{0}!", this.SomeBoolValue));

Perform action based on if statement using lambda

2 Answers2