Question

for instance, if I have this code:

if (foo != default(foo))
{ 
  int foo2 = foo; 
}

is there a way to shorten this to only the assignment? in pseudocode, something like:
foo2 = if not default foo

Answer 1

The problem with trying to shorten this is that foo2 is only valid within the scope inside your if statement. By moving this into one line, you’d always have to have foo2 defined in the outer scope, and it would always need some value.

If that is acceptable, you could use C#’s conditional operator:

int foo2 = foo != default(foo) ? foo : default(int);

Note that you need something for when foo == default(foo), as well, which becomes the final portion. With an int value, I would probably use : 0; at the end, but since you’re checking against default(foo), I’m assuming your “real use case” is probably not an Int32 value…

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Edit:

The (int) was an afterthought, in what I was actually trying I already had foo2 assigned so this is exactly what I was looking for.

Given this comment, you could do:

foo2 = foo != default(foo) ? foo : foo2;

This would effectively reassign foo2 if foo doesn’t have it’s default value, and leave it alone (assign it to itself) if it does.

That being said, I personally prefer something similar to your original:

// Assumes foo2 is already defined, based on your comment
if (foo != default(foo))
    foo2 = foo;

This is, in my opinion, far more clear in terms of your intent, and does avoid the extra assignment to yourself that you’re getting with a conditional operator.