add textbox number to array c#

Question

I'm trying to make this program where a user will input a number in a textbox and it will store it into an array.

So whenever the user clicks "calculate", it will get an average of all the numbers in the array. For some reason, when I try to run it, I get:

Additional information: Object reference not set to an instance of an object.

But then I can't initialize the array to specific length because I don't know how many numbers the user will input. So I was wondering is there a way to make it work without initializing a specific length for the array?

double[] numArray;
int count=0;

private void button1_Click(object sender, EventArgs e)
    {
        numArray[count] = convert.ToDouble(textBox1.Text);
        count++;
        displayNum.Visible = true;
        displayNum.Text = count.ToString();
         ;
    }

Misa Lazovic · Accepted Answer · 2015-10-18 01:24:37Z

2

Why are you using array if you don't know the size? Use list instead.

Initialization:

List<double> numList = new List<double>();

Adding to list:

numList.Add(some_element);

answered Oct 18, 2015 at 1:24

Misa Lazovic

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2 Comments

Huy Trinh Over a year ago

does a list work the same as an array like get the sum of all the number in the list. sorry i haven't learn how to use list yet in my class so i was just wondering.

Misa Lazovic Over a year ago

Pretty similar. In C# you have something called LINQ that can help you with tasks like that - sum, average, filtering out some elements etc. Google it, it's not too complicated

Cubicle.Jockey · Accepted Answer · 2015-10-18 01:24:36Z

1

Use a IList/List as these start off with a size but if you fill it up they will automatically grab more memory and grow.

IList<double> numArray = new List<double>(); 
int count=0;

private void button1_Click(object sender, EventArgs e)
{
    numArray.Add(convert.ToDouble(textBox1.Text));
    count++;
    displayNum.Visible = true;
    displayNum.Text = count.ToString();
}

answered Oct 18, 2015 at 1:24

Cubicle.Jockey

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Comments

stilloco · Accepted Answer · 2015-10-18 01:28:12Z

1

This is not possible with an array. An array needs to be initialized with the number of array items. Instead of an array I would suggest using List . This way you can add to the list without the restriction of defining how many items will be in it. If you need an array after you populated the I believe there is a ToArray method off of List.

answered Oct 18, 2015 at 1:28

stilloco

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