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Question

I have been running this syntax with one variable successfully, but now I am trying to change it to a foeach() loop and take a range of values and show the results as a message box. My issue with the syntax is that ecll always retains the value of the first number passed, and the calculation is never updated for each subsequent number in the array.

Where did I err that is preventing this from being updated for each subsequent number in the array?

private void btnGetData_Click(object sender, EventArgs e)
{
  int start = 2;
  int end = 10;

  int[] nums = Enumerable.Range(start, end - start).ToArray();

  foreach (int n in nums)
  {  
      float tp_x = 0, tp_y = 0;

      SAP = new List<PointF>();
      float fbw = m_pd.bl[m_pd.bl.Count - 1].m_Width;
      float Location1_X = tp_x + fbw;
      float Location1_Y = tp_y;
      SAP.Add(new PointF(Location1_X, Location1_Y));

      float iBH = gbh(m_pd.bl.Count - 1);
      float lbw = m_pd.bl[0].m_Width;
      float Location2_X = tp_x + lbw;
      float Location2_Y = tp_y + (iBH) + 1.5f;

      PointF rip = new PointF();
      if (!Getrip(ftp, rhep, ref rip))
      {
        SAP = null;
        return;
      }

      for (int iRowIndex = saii; iRowIndex < m_pd.pp.Count; iRowIndex++)
      {
        float Xvalue = m_pd.pp[iRowIndex].X;
        float Yvalue = m_pd.pp[iRowIndex].Y;
        SAP.Add(new PointF(Xvalue, Yvalue));

        if (Yvalue == LeftIntersectionPoint.Y)
        {
          pp.X = Xvalue;
          pp.Y = Yvalue;
          continue;
        }

        if (Xvalue >= rip.X)
        {
          Xvalue = rip.X;
          SAP[SAP.Count - 1] = new PointF(rip.X, rip.Y);
        }

        if (Xvalue == rip.X)
        {
          break;
        }

        pp.X = Xvalue;
        pp.Y = Yvalue;
      }

      double ecll = Getll(Location1_X, Location1_Y, rip.X, rip.Y);

      Messagebox.Show(Convert.ToString(ec11));
      txtLength.Text = ll.ToString("0.00");
    }
}

Answer 1

I feel like this is more of a comment based on what's going on here, but I kind of need the code section to explain this better I believe.

Let's simplify away from your points, widths, etc. I think we can all agree that n is never used within your function, so let's do a similar example:

So I have a function I wrote that adds 1 to 1

var newNum = 1 + 1;

It does what is expected, sets newNum to 2, but let's say I wanted to enhance it so that it adds 1 to the numbers in nums (from your original function):

int start = 2;
int end = 10;

int[] nums = Enumerable.Range(start, end - start).ToArray();

but if I try to reuse my function outright:

foreach (int n in nums)
{
  var newNum = 1 + 1;
} 

Every single pass, I'm always going to have newNum set at 2 because I'm not using the variable.

what I should do is write this:

foreach (int n in nums)
{
  var newNum = 1 + n;
} 

so based on your 2 through 10, I should see newNum set to 3 through 11 at various iterations.

Answer 2

Each iteration in the 'Foreach' loop assigns a new value to 'n'. However in the loop body, that value (n) is not used anywhere in the calculations (unless I am missing something). So, of course the result of these calculations will always be the same.

As soon as you include 'n' in some of the calclations, the result will change...