Does C# Have An Operation Similar to JavaScript's || Setter?

Question

Does C# have a similar operation to JavaScript's || setter?

For example, in JavaScript, if I want to check if a value is null and set a default, I can do something like this:

function foo(val){
    this.name = val || "foo";
}

But, when I want this functionality in C# I have to go this route:

public Foo(string val)
{
    this.name = (string.IsNullOrEmpty(val) ? "foo" : val);
}

I know this is petty and that beggars can't be choosers but, if at all possible, I'd like to avoid getting any answers that involve crazy hacks or extension methods. I'm fine with using the ternary operator, but I was just curious if there was a language feature I'd missed.

Update:

Great answers all around, but J0HN and Anton hit it on the head. C# doesn't do "falsy" values like JavaScript would in the example above, so the ?? operator doesn't account for empty strings.

Thanks for your time and the great responses!

Anton Gogolev · Accepted Answer · 2012-11-15 14:28:03Z

7

There's a null-coalescing operator in C#, though it can't handle all the quirkiness of JavaScript:

this.name = val ?? "foo";

Since an empty string is false in JavaScript, this C# code will behave differently from its JS counterpart.

answered Nov 15, 2012 at 14:28

Anton Gogolev

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1 Comment

Marcelo Zabani Over a year ago

It is worth mentioning that if val is an empty string, the OP will not achieve the desired result.

Bridge · Accepted Answer · 2012-11-15 14:30:32Z

2

There is a ?? operator that essentially is the same as COALESCE operator in SQL:

int? a = null; //int? - nullable int
int q = a??1; // q is set to one;

However, ?? does not check the string for emptiness, so it does not share the same meaning as javascript's ||, which treats empty strings as false as well.

edited Nov 15, 2012 at 14:30

Bridge

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answered Nov 15, 2012 at 14:29

J0HN

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2 Comments

elucid8 Over a year ago

I've got to go with your answer, @J0HN since you mentioned that it wouldn't evaluate "falsy" values like JavaScript.

J0HN Over a year ago

@elucid8, anyway, you should consider how an empty string should be treated. I've just recently faced a bug caused by using str!=null where !String.IsNullOrEmpty(str) should be.

Artem Vyshniakov · Accepted Answer · 2012-11-15 14:28:00Z

2

You can use ??:

private int Foo(string val){
    this.name = val ?? "foo";
}

answered Nov 15, 2012 at 14:28

Artem Vyshniakov

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1 Comment

Daniel A. White Over a year ago

this isn't the same as Foo.

Eric Herlitz · Accepted Answer · 2012-11-15 14:28:28Z

2

Go with this

this.name = val ?? "foo";

answered Nov 15, 2012 at 14:28

Eric Herlitz

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Comments

Uriil · Accepted Answer · 2012-11-15 14:28:35Z

1

Yep, use ??:

    private int Foo(string val){
        this.name = val ?? "foo";
    }

Check Msdn for more information: ?? Operator

answered Nov 15, 2012 at 14:28

Uriil

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