Call different function based on a boolean

Question

I have a boolean in my function that decide what function to call. Both of the function that are beying called giving back an Array.

Now in my eyes Hex[] areaHexes does exists but the compiler does not compile because it thinks its not set ( does not exists ).

How do I call one of both function properly based on what value bool semiRandom has?

void ElevateArea(int q, int r, int range, bool semiRandom = false, float centerHeight = 1f)
{
    Hex centerHex = GetHexAt(q, r);

    if (semiRandom) 
    { 
        Hex[] areaHexes = GetSemiRandomHexesWithinRangeOf(centerHex, range);
    } 
    else
    {
        Hex[] areaHexes = GetHexesWithinRangeOf(centerHex, range);
    }

    foreach (Hex h in areaHexes)
    {
        //if (h.Elevation < 0)
            // h.Elevation =  0;

        h.Elevation += 0.5f * Mathf.Lerp(1f, 0.25f, Hex.Distance(centerHex, h ) / range);
    }
}

Your `areaHexes` is being declared locally within your `if-else` blocks, it's not visible outside of the scope of those blocks. Declare it outside: `Hex[] areaHexes;` then `if (semiRandom) { areaHexes = ... } ...` etc. — lurker, Mar 16 '18 at 18:57

Jon Skeet · Accepted Answer · 2018-03-16T18:59:49.103

The reason it's not working is that you are currently declaring two local variables called areaHexes, each of which has a scope which is just the block they're declared in - so neither of them is in scope when you try to use them.

Brandon's answer (declaring the variable outside the if statement and then assigning to it from different places) will work fine - areaHexes is now in scope when you use it later. However, you can do it more simply with a conditional ?: operator:

Hex[] areaHexes = semiRandom
    ? GetSemiRandomHexesWithinRangeOf(centerHex, range)
    : GetHexesWithinRangeOf(centerHex, range);

Do this instead. It looks way more beautiful. – Brandon Miller Mar 16 '18 at 18:59 — Brandon Miller, Mar 16 '18 at 18:59

lurker · Answer 2 · 2018-03-16T19:05:28.767

Your areaHexes is being declared locally within your if-else blocks, it's not visible outside of the scope of those blocks. You have two different local areaHexes variables:

if (semiRandom) 
{
    // This definition of areaHexes is visible only within these { }
    //   and is not the same as the one in the else block below
    Hex[] areaHexes = GetSemiRandomHexesWithinRangeOf(centerHex, range);
} 
else
{
    // This definition of areaHexes is visible only within these { }
    //   and is not the same one as the one above
    Hex[] areaHexes = GetHexesWithinRangeOf(centerHex, range);
}

Declare it outside:

Hex[] areaHexes;

if (semiRandom) { 
    areaHexes = GetSemiRandomHexesWithinRangeOf(centerHex, range);
}
else {
    areaHexes = GetHexesWithinRangeOf(centerHex, range);
}

Or, use the tertiary ?: operator Jon showed.

You should look up variable scope rules for C#.

score 3 · Answer 3 · edited Mar 16 '18 at 18:58

3

Declare your array before your condition, like so:

Hex[] areaHexes;

if (semiRandom) 
{ 
    areaHexes = GetSemiRandomHexesWithinRangeOf(centerHex, range);
} 
else
{
    areaHexes = GetHexesWithinRangeOf(centerHex, range);
}

edited Mar 16 '18 at 18:58

maccettura

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answered Mar 16 '18 at 18:57

Brandon Miller

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Call different function based on a boolean

3 Answers3