how to reference array elements of class inside for loop?

Question

Newbie question here: I'm working with Flash Builder 4.5 on an Actionscript project. I've created the following classes:

package 
{
    public class ComplexNumber
    {
        public var real:Number;  // real component
        public var imag:Number;  // imaginary component
    }
}

and,

package 
{
    public class ComplexArray
    {
        public var real:Array;  // real component array
        public var imag:Array;  // imaginary component array
    }
}

and a static function:

package 
{
    public class ComplexDivide
    {
        public static function v1p0(a:Number, b:Number, // numerator: a+bi
                                    c:Number, d:Number  // denominator: c+di
                                    ):ComplexNumber
        {
            var z:ComplexNumber = new ComplexNumber();  
            var divisor:Number = c*c + d*d;

            z.real = (a*c + b*d) / divisor; // real component
            z.imag = (b*c - a*d) / divisor; // imaginary component          

            return z;
        }
    }
}

and in another .as file I'm trying to call this function

var BXFN_complex:ComplexArray = new ComplexArray();
for (var ii:int = 0; ii <= 2; ii++) {
    BXFN_complex[ii] = ComplexDivide.v1p0( 1, 0, 2, 3 );
}

but the code inside this loop generates the following run time error: "ReferenceError: Error #1056: Cannot create property 0 on ComplexArray." Thus, my code for "BXFN_complex[ii] = ~" is incorrect. Anyone know how to achieve what I'm trying to do? Basically, ComplexDivide.v1p0 returns two numbers, and BXFN_complex is an object containing two number arrays, and I want to assign the ComplexDivide two numbers into the ii'th element of arrays in BXFN_complex.

weltraumpirat · Accepted Answer · 2011-11-13 00:59:36Z

2

I am not sure I understand what you are trying to accomplish, and frankly I find your code hard to read, but the cause of the error is simple:

Your ComplexArray instance does not behave like an Array - it is an Object with two member Arrays, real and imag, and you need to specify which one you are acually addressing:

BXFN_complex.real[ii]

or

BXFN_complex.imag[ii]

instead of just

BXFN_complex[ii]

If you want to pass in just a ComplexNumber type, you can use a function to do it:

(on ComplexArray):

public function setItemAt (index:int, n:ComplexNumber) : void {
    real[index] = n.real;
    imag[index] = n.imag;
}

Don't forget to initialize the real and imag arrays before adding items!

Last but not least I don't understand why you don't use a primitive array which holds ComplexNumbers, instead of a ComplexArray which holds two arrays of primitive Number values - then you could just use BXFN_complex[ii]like you did before.

edited Nov 13, 2011 at 0:59

answered Nov 13, 2011 at 0:37

weltraumpirat

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1 Comment

ggkmath Over a year ago

Thanks Weltraumpirat, I took your last suggestion, which is working out.

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