Simplifing a nested IF statement

Question

I have a function that is like the following

string Foo(bool A, bool B)
{
    if(A)
    {
        if(B)
        {
            return "W";
        }
        else
        {
            return "X";
        }
    }
    else
    {
        if(B)
        {
            return "Y";
        }
        else
        {
            return "Z";
        }
    }
}

That double nesting just feels wrong to me. Is there a better way to implement this pattern?

Thank you everyone for helping, I end up going with the trinary route. It helped turn this:

if (female)
{
    if (nutered)
    {
        destRow["TargetSex"] = "FS";
    }
    else
    {
        destRow["TargetSex"] = "F";
    }
}
else
{
    if (nutered)
    {
        destRow["TargetSex"] = "MN";
    }
    else
    {
        destRow["TargetSex"] = "M";
    }
}

in to this

destRow["TargetSex"] = female ? (nutered ? "FS" : "F")
                              : (nutered ? "MN" : "M");

@DavidStarkey There are 4 possible result states, you only return 3. — Scott Chamberlain, May 02 '13 at 22:18
Then `if(A && B) { } else if (!A && B) { } else if (B) { } else { }` — David Starkey, May 02 '13 at 22:19
@DavidStarkey: Which of course should read: `if(A && B) { } else if (A) { } else if (B) { } else { }`. — Pieter Geerkens, May 02 '13 at 22:25

Steven Wexler · Accepted Answer · 2013-05-02T22:33:51.010

10

if (A)
{
    return B ? "W" : "X";
}
return B ? "Y" : "Z";

Or even more terse:

return A ? (B ? "W" : "X")  
         : (B ? "Y" : "Z");

If your going for exclusively unnested conditions:

if (A && B) return "W";
if (A && !B) return "X";
return B ? "Y" : "Z";

edited May 02 '13 at 22:33

answered May 02 '13 at 22:16

Steven Wexler

16,589
8
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2

Can even do `return A ? (B ? "W" : "X") : (B ? "Y": "Z")`. – SimpleVar May 02 '13 at 22:18
@Yorye That loses a bit of readability for me (personally), and might be overdoing it. – doppelgreener May 02 '13 at 22:22
2

The "even more terse" solution is the one I like most. – Scott Chamberlain May 02 '13 at 22:24
2

When using the `even more terse` version, I like to put the colon from the end of the first line right under the question mark after the 'A'. To my eye that scans best of the various placement options. – Pieter Geerkens May 02 '13 at 22:29
@PieterGeerkens see my updated question, I included the real version and how I did it, I did exactly what you suggested already :) – Scott Chamberlain May 02 '13 at 22:30
@PieterGeerkens +1 I really like that syntax. I'll edit my answer. – Steven Wexler May 02 '13 at 22:33

score 3 · Answer 2 · answered May 02 '13 at 22:18

3

Logically, no. You have 4 distinct conditions for two variables.

You can make the code more concise, though:

string Foo(bool A, bool B)
{
    return A ? 
      B ? "W" : "X"
        :
      B ? "Y" : "Z";

}

Or if you're feeling particularly evil, put it on one line with no parens!:

return A?B?"W":"X":B?"Y":"Z";

answered May 02 '13 at 22:18

D Stanley

149,601
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I was looking for better conciseness, I knew there is no logic simplification. – Scott Chamberlain May 02 '13 at 22:19
1

Those two are tied for the ugliest options I can think of! Do you wear striped ties with your plaid jackets also? +1 for the courage to post those two. – Pieter Geerkens May 02 '13 at 22:32
@PieterGeerkens to be fair, he was the first one to post a trianary solution, steaks posted his in later as a edit. – Scott Chamberlain May 02 '13 at 22:33

score 0 · Answer 3 · answered May 02 '13 at 22:17

0

You four possible states. A shorter (though not necessarily easier-to-maintain) representation would be

if (A && B) {
    return "W";
} else if (A && !B) {
    return "X";
} else if (!A && B) {
    return "Y";
else return "Z";

answered May 02 '13 at 22:17

Eric J.

147,927
63
340
553

score 0 · Answer 4 · answered May 02 '13 at 22:39

0

I just have to throw this in for fun:

    string Foo(bool A, bool B)
    {
        var labels = new[]{"W", "X", "Y", "Z"};
        return labels[(A ? 0 : 2) + (B ? 0 : 1)];
    }

answered May 02 '13 at 22:39

Scott Jones

2,880
13
19

Clever, When I was originally trying to think of better ways to do it I was actually thought about a similar idea but using a switch statement instead of an array :). – Scott Chamberlain May 02 '13 at 22:41

Simplifing a nested IF statement

4 Answers4