选择数组vb中的特定项目

Question

I have the text file with year numbers and a line return then another number.

Year 1991
8
Year 1990
14

An array carries the year number and another one carries the number below it.

strYear(intCount) = objReader.ReadLine()
dblSum(intCount) = Convert.ToDouble(objReader.ReadLine())

The user selects the year from a combo box and I have it outputted I just don't know how to output the apparent number from the year selected.

Answer 1

You can use the SelectedIndex of the ComboBox as an index into the array.

Dim sum = dblSum(myComboBox.SelectedIndex)

That said, instead of doing it that way, why not add both values to one object, put those objects in a list and then bind that list to the ComboBox . You could then get the sum value directly from the SelectedValue property of the ComboBox . Eg

Dim items As New List(Of Tuple(Of String, Double))

'...

items.Add(Tuple.Create(objReader.ReadLine(), Convert.ToDouble(objReader.ReadLine()))

'...

With myComboBox
    .DisplayMember = "Item1"
    .ValueMember = "Item2"
    .DataSource = items
End With

'...

Dim sum = CDbl(myComboBox.SelectedValue)

It's convenient to use Tuples here but you can use a class or structure of your own if you prefer.

Answer 2

As you're reading alternate lines from your text file into two arrays (years first, numbers second) the index into the second array of numbers should be the same as the index into the first array of years.

If the first array of years is used to directly populate your combobox, then the selected index of the combo will also be the index into the array of numbers for the number associated with the selected year.

So dblSum(myComboBox.SelectedIndex) would give you the correct number.