Manipulating information stored in array

Question

I have a lot of data stored in multiple arrays that I would like to get a value from but I'm having trouble. The identifier arrays are

String[] seqNum2 = new String[600];
String[] seqNum = new String[600];

I want to be able to find the match data in those arrays and get information that aligns with the data in these arrays

String[] netOil2 = new String[600];
String[] netOil = new String[600];

So here is my code so far but it is not outputting the correct answer that I want, all it is outputting is an infinite loop that says "System.String[], NaN".

    private void netOilRadBtn_CheckedChanged(object sender, EventArgs e)
    {
        StreamWriter sw = new StreamWriter("test.txt"); //testing purposes only
        //StreamReader sr = new StreamReader("OUTPUT.CSV");
        double first;
        double second;


        for (int i = 0; i < netOil2.Length; i++)
            {
                for (int j = 0; j < netOil.Length; j++)
                {
                    if (seqNum2[i] == seqNum[j])
                    {
                        //sw.WriteLine("Find New Seq Num");
                        first = Convert.ToDouble(netOil2[i]);
                        second = Convert.ToDouble(netOil[j]);

                        double answer = (first - second) / first;

                        sw.WriteLine("{0}, {1}", seqNum2, answer);
                    }
                }
            }

    }

All I want to be able to do is output the matching seqNum and then the double answer. Any help would be greatly appreciated.

I think you need to write current item from array sw.WriteLine("{0}, {1}", seqNum2[i], answer); — Sergey Berezovskiy
– Sergey Berezovskiy, Commented Jun 4, 2013 at 14:53
It can't actually be an infinite loop, though it will print that out 600 x 600 = 360000 times. I can see why you might think it's infinite, but it will even eventually exit. — p.s.w.g
– p.s.w.g, Commented Jun 4, 2013 at 14:55
Paired arrays like that are an anti-pattern. don't do it. Define a class that has a seqNum and netOil property, and then have collections of that class type. — Joel Coehoorn
– Joel Coehoorn, Commented Jun 4, 2013 at 14:55

Zdeslav Vojkovic · Accepted Answer · 2013-06-04 15:16:48Z

2

So, this line:

sw.WriteLine("{0}, {1}", seqNum2, answer);

outputs System.String[], NaN.

seqNum2 is an array, that's why you get System.String[] in the output. You probably wanted seqNum2[i] if you want to see the element of seqNum2 which is currently being processed. Of course, since you are not initializing the array elements (see below), even with this change you won't see what you expect, as the value is null and it is formatted to an empty string, so you will get , Nan as output.

The reason you get NaN in output is line:

double answer = (first - second) / first;

I guess that first and second are both 0. If only first were 0, you would get Infinity, and otherwise you would get 0.

These values are set to 0 most likely because you don't set string values in netOil and netOil2 arrays, so you have 600 nulls and Convert.ToDouble(null) returns 0.

Debug your code, and see on what values you call Convert.ToDouble and what is the returned value.

edited Jun 4, 2013 at 15:16

answered Jun 4, 2013 at 14:56

Zdeslav Vojkovic

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3 Comments

Stock Over a year ago

I changed it to seqNum2[i] but now it's not outputting anything

Zdeslav Vojkovic Over a year ago

sure, what value would you expect?

Zdeslav Vojkovic Over a year ago

which happens to have the value of?

Joel Coehoorn · Accepted Answer · 2013-06-04 15:18:42Z

1

private void netOilRadBtn_CheckedChanged(object sender, EventArgs e)
{
    using (var sw = new StreamWriter("test.txt")) //testing purposes only
    { 
        //StreamReader sr = new StreamReader("OUTPUT.CSV");

        var items =  netOil.Zip(seqNum, (oil, seq) => new {Oil = oil, Seq = seq});
        var items2 =  netOil2.Zip(seqNum2, (oil, seq) => new {Oil = oil, Seq = seq});

        foreach (var item in items.Join(items2,
                     i=>i.Seq,i=>i.Seq, (a,b)=>
                     {
                         double first = Convert.ToDouble(a.Oil);
                         double second = Convert.ToDouble(b.Oil);

                         double answer = (first - second) / first;
                         return string.Format("{0}, {1}", a.Seq, answer);
                     }))

        { 
            sw.WriteLine(item);
        }
    }
}

edited Jun 4, 2013 at 15:18

answered Jun 4, 2013 at 15:05

Joel Coehoorn

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1 Comment

Stock Over a year ago

@Joel this gives me an error on the if statement "cannot implicity convert type 'string' to 'bool

Nikola Dimitroff · Accepted Answer · 2013-06-04 14:58:54Z

0

You get "System.String[]" since you are calling Array.ToString(). You get NaN since obviously answer is NaN. My guess is that one of those

                    first = Convert.ToDouble(netOil2[i]);
                    second = Convert.ToDouble(netOil[j]);

returns NaN. Put a breakpoint in those lines and check whether the values of netOil2[i] netOil[j] actually represent numbers (keep in mind that what Convert.ToDouble returns is based on your current culture).

answered Jun 4, 2013 at 14:58

Nikola Dimitroff

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DonBoitnott · Accepted Answer · 2013-06-04 15:08:06Z

0

Instead of pair arrays, I would use Dictionary collections.

For example:

Dictionary<Int32, Double> dictOil1 = new Dictionary<Int32, Double();
Dictionary<Int32, Double> dictOil2 = new Dictionary<Int32, Double();

//If seqNum and netOil _really are_ strings...
Int32 seq, seq2;
Double oil, oil2;
if (Int32.TryParse(seqNum, out seq) && Double.TryParse(netOil, out oil))
    dictOil1.Add(seq, oil);
if (Int32.TryParse(seqNum2, out seq2) && Double.TryParse(netOil2, out oil2))
    dictOil2.Add(seq2, oil2);

answered Jun 4, 2013 at 15:08

DonBoitnott

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