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POOverride array size in subclass
 

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    <p>I have an array as a member of a class. In a subclass, I would like to re-define the array with a different size. I want to do this because I anticipate making many subclasses, each with only the array size it needs, and nothing more. </p> <pre><code>class Foo { Foo() {ivar = 1}; int thisArray[2]; int ivar; } class Bar : public Foo { Bar() {ivar = 3}; int thisArray[4]; } int main() { Foo myFoo; Bar myBar; Foo fooCollection[] = {myFoo,myBar}; cout &lt;&lt; "myFoo array size = " &lt;&lt; sizeof(myFoo.thisArray)/sizeof(int) &lt;&lt; endl; cout &lt;&lt; "myBar array size = " &lt;&lt; sizeof(myBar.thisArray)/sizeof(int) &lt;&lt; endl; for (int n=0;n&lt;2;n++) { cout &lt;&lt; "fooCollection[" &lt;&lt; n &lt;&lt; "] array size = "; cout &lt;&lt; sizeof(fooCollection[n].thisArray)/sizeof(int) &lt;&lt; endl; } for (int n=0;n&lt;2;n++) { cout &lt;&lt; "fooCollection[" &lt;&lt; n &lt;&lt; "] ivar = "; cout &lt;&lt; fooCollection[n].ivar &lt;&lt; endl; } } </code></pre> <p>My results are:</p> <pre><code>myFoo array size = 2 myBar array size = 4 fooCollection[0] array size = 2 fooCollection[1] array size = 2 fooCollection[0] ivar = 1 fooCollection[1] ivar = 3 </code></pre> <p>I get that, since I declare the array objects as objects of class <code>Foo</code>, that referring to <code>myBar</code> within that scope would reference <code>myBar</code> as though it was a <code>Foo</code> and consequently interpret the size of <code>thisArray</code> as equivalent to 2. I also understand why <code>ivar</code> comes out the way it does. </p> <p>Is there a way to affect the size of <code>thisArray</code> within the <code>Bar</code> class so its "correct" size can be recognized within an array of <code>Foo</code> objects? I would use a vector, but they are not friendly on the arduino platform. I could also simply make the array within the Foo class with a size of 100, but I am trying to be conscious of memory allocation.</p>
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    1. UStorrential coding
    1. USRyan Tuck
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    1. COUnrelated, but important: Look up "constructor initializer lists".
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      1. USKerrek SB
    2. COIs there a reason you need to use polymorphism?
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      1. USpaddy
    3. COIs there a reason why you don't want to use the STL containers that take care of all this re-allocation for you?
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      1. USLieuwe
 

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