Index was outside the bounds of array in graph plotting c#

Question

I'm trying to make a graph between instant charge against time, and I'm getting this error:

Index was outside the bounds of array

My code is below:

namespace WindowsFormsApplication19
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double max = 24000000, min = 23999999.85;
            double[] q = new double[9];
            int t = 0;
            for (t = 1; t <= 10; t++)
            {
                q[t] = (24 * Math.Pow(10, 6)) * Math.Exp(-t / (2000 * Math.Pow(10, 6)));
                chart1.Series[0].Points.AddXY(t, q[t]);
            }

            chart1.ChartAreas[0].AxisY.Maximum = max;
            chart1.ChartAreas[0].AxisY.Minimum = min;
            chart1.Series[0].ChartType = SeriesChartType.FastLine;
            chart1.Series[0].Color = Color.Red;
        }
    }
}

I tried this but am still having the same problem:

private void button1_Click(object sender, EventArgs e) {

    double[] q = new double[9];
    int t = 0;
    for (int i = 0; i <= 9; i++)
    {
        for (t = 1; t <= 10; i++)
        {
            q[i] = (24 * Math.Pow(10, 6)) * Math.Exp(-t / (2000 * Math.Pow(10, 6)));
            chart1.Series[0].Points.AddXY(t, q[i]);
        }
    }

}

Array indexes are 0 based. Start from 0 to 8. Note that q length is 9. So you should start from 0 to 8 NOT 1 to 10 — M.kazem Akhgary
– M.kazem Akhgary, Commented Nov 11, 2015 at 23:30

Derek · Accepted Answer · 2015-11-12 00:10:54Z

1

Inside the for loop it is much more standard to go from 0 to < q.Length.

That way you can change the length of your array and the for loop will still work.

        double[] q = new double[9];
        for (int t = 0; t < q.Length; t++)
        {
            q[t] = (24 * Math.Pow(10, 6)) * Math.Exp(-t / (2000 * Math.Pow(10, 6))); 
            chart1.Series[0].Points.AddXY(t, q[t]);               
        }

answered Nov 12, 2015 at 0:10

Derek

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Comments

Josef Engelfrost · Accepted Answer · 2015-11-12 00:33:23Z

0

Index out of bounds means that your code is trying to write to an index that is higher than the highest index.

You have 2 problems in your code that cause this - you need to fix both before it will work.

1. Fix q

In your code you have an array q which has 9 indexes, from 0 to 8, but it looks like you want 10: new double[10].

2. Fix the loop

In your for look you loop from 1 to 10, but arrays start with index 0 (you have 10 indexes, from 0 to 9). You need t to start with 0, not 1.

namespace WindowsFormsApplication19
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double max = 24000000, min = 23999999.85;
            double[] q = new double[10]; // Fix q: length of 10
            for (int i = 0; i < q.Length; i++) // Fix loop: start at 0
            {
                int t = i + 1; // Fix loop: t and i need to have different values
                q[i] = (24 * Math.Pow(10, 6)) * Math.Exp(-t / (2000 * Math.Pow(10, 6)));
                chart1.Series[0].Points.AddXY(t, q[i]);
            }

            chart1.ChartAreas[0].AxisY.Maximum = max;
            chart1.ChartAreas[0].AxisY.Minimum = min;
            chart1.Series[0].ChartType = SeriesChartType.FastLine;
            chart1.Series[0].Color = Color.Red;
        }
    }
}

edited Nov 12, 2015 at 0:33

answered Nov 11, 2015 at 23:33

Josef Engelfrost

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11 Comments

Amad Khan Over a year ago

thanks but still having an error of "Index was outside the bounds of array" at t = 10. graph is showing only value from t = 1 to 9 but at t= 10 it is showing an error

Josef Engelfrost Over a year ago

Have you forgotten to change one of the q[t] to q[i]? Or is t supposed to start at 0 as well?

Amad Khan Over a year ago

no i've changed all q[t] to q[i] and t is not supposed to start at 0 it should start from 1 to 10

Amad Khan Over a year ago

while debugging it i saw that it is showing error of " Index was outside the bounds of the array" in my formula at t = 10

Josef Engelfrost Over a year ago

Hm.. Not sure if this is your problem, but I see a mistake in my for loop. for (int i = 0; t < q.Length; i++), it should of course be for (int i = 0; i < q.Length; i++)

|

ercyon · Accepted Answer · 2015-11-11 23:36:58Z

0

your array can contain 10 elements since:

double[] q = new double[9];

when your for loop hits 10; it means you want to reach q[10] so it will result in Index was outside the bounds of array error.

you shouldn't increment your loop index more than 9.

answered Nov 11, 2015 at 23:36

ercyon

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