CODEWITHSUNDEEP
c#winforms
Kevin Gichia
Kevin Gichia

Reputation: 57

Set combobox selected index/item according to a condition

The comboBox9 gets populated with unique values from an Excel Range with the code below.

            comboBox9.Items.Clear();
            HashSet<string> distinct = new HashSet<string>();


            foreach (_Excel.Range cell in range.Cells)
            {
                string value = (cell.Value2).ToString();

                if (distinct.Add(value))
                    comboBox9.Items.Add(value);
            }

What i tried to do unsuccessfully is set the index of the combobox9 with the first item that satisfies the if condition .

            foreach (string item in comboBox9.Items)
            {
                if (278 * Variables.m3h / (Math.Pow(int.parse(item) / 2, 2) * 3.14) > Variables.maxvelocity)
                {
                    comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item);
                }
            }

Any ideas on where i'm going wrong ?

Upvotes: 0

Views: 771

Answers (3)

Srijon Chakraborty
Srijon Chakraborty

Reputation: 2164

I think your code might get an exception of "Specified cast is not valid" in the line of

comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item); because you are adding the items in comboBox9 as "string" type and using "int" type in foreach (int item in comboBox9.Items). So, Please Check your code. I am going to paste 2 different codes below both for int type and string type.
//FOR INT TYPE

  void ComboLoadAndSelectIndex()
  {
        comboBox9.Items.Add(1);
        comboBox9.Items.Add(10);
        comboBox9.Items.Add(20);

        
        foreach (int item in comboBox9.Items)
        {
            if (item == 10)//your math Condition
            {
                comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item);
            }
          
        }
  }

//FOR String Type

 void ComboLoadAndSelectIndex()
 {
        comboBox9.Items.Add(1.ToString());
        comboBox9.Items.Add(10.ToString());
        comboBox9.Items.Add(20.ToString());

        foreach (string item in comboBox9.Items)
        {
            if (item == 10.ToString())//your math Condition
            {
                comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item);
            }
        }
  }

NOTE: Both codes are works fine in Winforms Application. Please check and try it.

Upvotes: 1

Kevin Gichia
Kevin Gichia

Reputation: 57

Figured it out :

            comboBox9.Items.Clear();
            HashSet<string> distinct = new HashSet<string>();


            foreach (_Excel.Range cell in range.Cells)
            {
                string value = (cell.Value2).ToString();

                if (distinct.Add(value))
                    comboBox9.Items.Add(value);
            }

            if (comboBox9.Items.Count > 1)
            {
                foreach (string item in comboBox9.Items)
                {
                    if (278 * Variables.m3h / (Math.Pow(int.Parse(item) / 2, 2) * 
                       3.14) < Variables.maxvelocity)
                    {
                        comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item);
                        break;
                    }
                }
            }
            else
            {
                comboBox9.SelectedIndex = -1;
            }

Upvotes: 0

vernou
vernou

Reputation: 7610

All items match the condition will be selected. Because the selection unique, the last selected item is displayed.

When the first item is selected, you need stop the selection :

foreach (int item in comboBox9.Items)
{
    if (278 * Variables.m3h / (Math.Pow(item / 2, 2) * 3.14) > Variables.maxvelocity)
    {
        comboBox9.SelectedIndex = comboBox9.Items.IndexOf(item);
        break; // a item is selected, then stop the selection
    }
}

Upvotes: 1

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