Getting the index of an item inside listview vb.net - vb.net

Question

how do i get the index of an item inside the listview by looping?
for i = 0 to Listview1.items.count -1
??????????????????
next
so that i can get the index and validate it.
i know how to get the index using selectedindices.
i really wanna know how to get the index in a looping method
just want to clarify
i was working on a listview that have a hotkeys from keypress 0 to 9
when keypress 0 is pressed, item1 will be inserted inside the listview and if i pressed 0 again the quantity column will increment, i manage to do that. but the problem is when i press keypress 1 first (which has the item2) it will go inside the listview then if i press keypress 0 im having an error because of the incriminating of the quantity. i think finding the index and loop it will solve the problem.
this is how i manage to incriment the quantity of the item1 in column 4 or element(3)
Dim quantity As Integer = CInt(cartListView.Items(0).SubItems.Item(3).Text)
quantity = quantity + 1
cartListView.Items(0).SubItems.Item(3).Text = quantity.ToString
of course the index(0) gives me error when the item1 is in the index 1 of the listview
please be reminded that the item1 is static or fixed in the keypress 1. any solution or revision?
Solved:
since the item1 is static, the looping statement that vlad gave does it. it manage to search the item1 and return the index and inserted that index to the element 0 of this code
Dim textSearch = DTfsn.Rows(0)("item1").ToString 'static item for keypress 1
For i = 0 To cartListView.Items.Count - 1
If cartListView.Items(i).Text = textSearch Then
Dim quantity As Integer = CInt(cartListView.Items(i).SubItems.Item(3).Text)
quantity = quantity + 1
cartListView.Items(i).SubItems.Item(3).Text = quantity.ToString
End If
Next
now it can increase its quantity whereever the item1 is positioned in the listview.

Answer 1

starting from this comment
of course. i wanna know how to get the index of a searched item
I'll just guess
if you want to find the index of a specific item (in the example I'm searching for item d)
you can do something like this:
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim textSearch = TextBox1.Text 'text to look for
For i = 0 To ListView1.Items.Count - 1
If ListView1.Items(i).Text = textSearch Then
MessageBox.Show("text found at index " & i.ToString)
End If
Next
End Sub