Visual Basic - Counting the occurrence of numbers from a random array - vb.net

Question

I need to use arrays and strings. The program should just search for 1 number which the user will enter (0-9). Here is my code below. It uses an array to get a random number, and it's testing the occurrences for each number. However it's not working, but I don't need it to test for every number anyway.
The program must only test for the 1 number that the user requests. So if the random number that's generated is say.. '7417', and user user has chosen '7', then the program will report back there have been two sevens. I'm going to use a textbox 'txtEnter' to get the users number to search for. Can anyone help me? Thanks!
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Randomize()
Dim ArrayNum(1) As Integer
ArrayNum(0) = Int(Rnd() * 100000)
lblDisplayNumber.Text = ArrayNum(0)
Dim num As Integer
txtEnter.Text = num
Dim counts = From c In num.ToString()
Group By c Into Group
Select DigitGroup = New With {.Count = Group.Count(),
.Digit = c, .Group = Group}
Order By DigitGroup.Count Descending
Select String.Format("There are {0} number {1}'s found.",
DigitGroup.Count, DigitGroup.Digit)
Dim message = String.Join(Environment.NewLine, counts)
End Sub

Answer 1

If you want to use Linq, it's short and readable:
Dim counts = From c In num.ToString()
Group By c Into Group
Select DigitGroup = New With {.Count = Group.Count(), .Digit = c, .Group = Group }
Order By DigitGroup.Count Descending
Select String.Format("There are {0} number {1}'s found.",
DigitGroup.Count, DigitGroup.Digit)
Dim message = String.Join(Environment.NewLine, counts)
Update: Here is a complete sample which shows the result of the entered number and a summary:
Dim rnd As New Random()
Dim randomInt = rnd.Next(0, 100000)
lblDisplayNumber.Text = randomInt.ToString()
Dim num As Integer
If Int32.TryParse(txtEnter.Text, num) AndAlso num >= 0 AndAlso num < 10 Then
Dim counts = From c In randomInt.ToString()
Group By c Into Group
Select DigitGroup = New With {.Count = Group.Count(), .Digit = c, .Group = Group}
Order By DigitGroup.Count Descending, DigitGroup.Digit
Dim numCount = counts.FirstOrDefault(Function(grp) grp.Digit.ToString() = num.ToString())
If numCount IsNot Nothing Then
Dim numMessage = String.Format("There are {0} number {1}'s found.", numCount.Count, num)
MessageBox.Show(numMessage)
Else
MessageBox.Show("Number does not contain " & num)
End If
Dim summaryCount = From grp In counts
Select String.Format("There are {0} number {1}'s found.", grp.Count, grp.Digit)
Dim summaryMessage = String.Join(Environment.NewLine, summaryCount)
MessageBox.Show("Summary:" & Environment.NewLine & summaryMessage)
Else
MessageBox.Show("Please enter a number between 0 and 9.")
End If

Answer 2

Your code has several issues, but to give you an answer directly to what is missing:
you should convert your random number to a string first
Number= Int(Rnd() * 100000)
NumberString = Number.ToString()
convert that string to an array of characters
DigitArray = NumberString.ToCharArray()
then loop over all characters of the array and convert each character c back to an integer
For Each c As Char In DigitArray
num = c - "0"C`
Then use that num as index for your counts array
count(num)+=1
instead of that horrible switch statement. I let you figure out the correct Dimstatements for those variables.

Answer 3

The solutions presented earlier seem a bit complicated if you just need to find how many times the entered number is in the random digits.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' create the data
Dim nDigits As Integer = 5
Dim digits(nDigits - 1) As String
For i = 0 To nDigits - 1
digits(i) = CInt(Rnd() * 10).ToString
Next
' show the data
TextBox1.Text = String.Join("", digits)
Dim inp = InputBox("Enter a number from 0 to 9")
' count the occurrences of the entered number
Dim nFound = digits.Count(Function(d) d = inp)
MsgBox(String.Format("There are {0} occurrences of {1}.", nFound, inp))
End Sub