Any ways to swap variables within if-statement better than this?

Question

I'm writing a small C# console app, and I was wondering if there are ways to improve this part of code (particullary how to make it comply with the principle "Don't repeat yourself"). My app works fine with this construction too, but I don't like how it looks like.

if (rows % 2 == 0)
{
    evenCell = '#';
    oddCell = '.';
}
else
{
    evenCell = '.';
    oddCell = '#';
}

Ternary expression: `(evenCell, oddCell) = rows % 2 == 0 ? ('#', '.') : ('.', '#');` — Lasse V. Karlsen, Jun 12 '20 at 15:06
In newer versions of C# you can use tuples and tuple assignments to assign multiple variables "at the same time" (it's a bit of trickery but the syntax *means* that). Thus you either do a tuple assignment using one tuple with values, or with another tuple with different values. Tuple assignments (I'm sure it has a proper term) also allows you to swap variables: `(a, b) = (b, a);` will swap the contents of `a` and `b`. — Lasse V. Karlsen, Jun 12 '20 at 15:31
Having said all of that, remember that you need to *maintain* this code. If every time you get back to this code you scratch your head (or beard, or leg, or parrot, or ... ) and wonder "what the he** does this do?", then perhaps it should've stayed as an if-statement. :) — Lasse V. Karlsen, Jun 12 '20 at 15:32
@LasseV.Karlsen haha, this is a golden qoute. Indeed, "readability over brevity" seems to be a healthy practice. However, learning how to use new tools in my opinion is important as well, so I will really try to dig into ternary expressions. Thank god we can leave comments in the code :D — Alexey Bogdan, Jun 12 '20 at 19:03
Personally I feel that comments are a blessing in disguise. It allows us to keep the bad code, just write what it actually does, instead of refactoring the code so that it makes sense on its own. But, that's just **my** opinion, the important part is that you find **your** opinion. Personally I would use my code from my comment, but others might not. — Lasse V. Karlsen, Jun 12 '20 at 19:12

Pavel Anikhouski · Answer 1 · 2020-06-30T12:10:37.930

2

You can use conditional operator ?: for that

var evenCell = rows % 2 == 0 ? '#' : '.';
var oddCell = rows % 2 == 0 ? '.' : '#';

It's shorter, but in this case you evaluate rows % 2 expression twice

You can also use C# 8 switch expression with tuple pattern

var (evenCell, oddCell) = (rows % 2) switch
{
    0 => ('#', '.'),
    _ => ('.', '#')
};

Or just conditional operator with value tuple (it works starting from C# 7)

var (evenCell, oddCell) = rows % 2 == 0 ? ('#', '.') : ('.', '#');

edited Jun 30 '20 at 12:10

answered Jun 12 '20 at 14:51

Pavel Anikhouski

21,776
12
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It's shorter, but now you're having to evaluate `rows % 2` twice. – itsme86 Jun 12 '20 at 14:52
@PavelAnikhouski I've been thinking about this too but gave up on this idea for a reason **itsme86** mentioned. – Alexey Bogdan Jun 12 '20 at 14:55
@AlexeyBogdan You can also use C# 8 `switch` expression with tuple pattern, I've added this to the answer (if you can target this language version). It's short as well and doesn't have code duplication – Pavel Anikhouski Jun 12 '20 at 15:00
@PavelAnikhouski I will defenitly read documentation on this topic. Thank you for help! – Alexey Bogdan Jun 12 '20 at 15:04

score 1 · Accepted Answer · answered Jun 12 '20 at 14:52

1

Maybe the short version is better like this :

(rows % 2 == 0) ? (evenCell = '#'; oddCell = '.';) : ( evenCell = '.';  oddCell = '#');

answered Jun 12 '20 at 14:52

Ali Kianoor

1,167
9
18

1

Looks kind of long, but here the check is done once and I don't see any repetition. I will mark this as an answer, thank you! – Alexey Bogdan Jun 12 '20 at 15:01

Any ways to swap variables within if-statement better than this?

2 Answers2