Visual Basic Selection using a case statement task check - vb.net

Question

Just wondering if what I've done for my visual basic computing homework is correct. Our activity task:
"Activity: Grade Selection using a Case statement
Introduction:
You will use a case statement that will allow a user to enter a grade value as an integer value and return the grade as a letter ranging from A to E.
Selection Logic
If the number entered is between 91-100 the output will be A
If the number entered is between 81 and 90 the output will be B
If the number entered is between 71 and 80 the output will be C
If the number entered is between 61 and 70 the output will be D
If the number entered is between 51 and 60 the output will be E
Anything lower than 50 is a fail
Anything higher than 100 is an incorrect value and they will have to run the program again.
Create the necessary variables
Create necessary outputs telling the user the purpose of the program
Create the code to read in the user's first name
Create the code that reads in the grade as an integer value
Create the code that produces the relevant grade based on the above criteria.
Create the necessary output code to output the user's first name and their grade as a letter of the alphabet"
My code:
Module Module1
Sub Main()
Dim anum As Integer
Dim name As String
Console.WriteLine("This programme converts marks into grades")
Console.WriteLine("Please enter name...")
name = Console.ReadLine
Console.WriteLine("Please enter number of marks...")
anum = Console.ReadLine()
Select Case anum
Case 91 To 100
Console.WriteLine(name & " receives an A.")
Case 81 To 90
Console.WriteLine(name & " receives a B.")
Case 71 To 80
Console.WriteLine(name & " receives a C.")
Case 61 To 70
Console.WriteLine(name & " receives a D.")
Case 51 To 60
Console.WriteLine(name & " receives an E.")
Case Is <= 50
Console.WriteLine(name & ", unfortunately failed.")
Case Is > 100
Console.WriteLine(name & ", this is an incorrect value. Please try again.")
End Select
End Sub
End Module
Would be thankful if someone could just confirm it is correct or tell me if I have done something wrong or need to add something!
Thanks.

Answer 1

Original code seems to be ok Just I've improved it using the correct datatypes, adding basic exception castings, and trying to simplify things:
Module Module1
' Store ranges and chars
ReadOnly TupleList As New List(Of Tuple(Of Short, Short, Char)) From { _
Tuple.Create(51S, 60S, "E"c), _
Tuple.Create(61S, 70S, "D"c), _
Tuple.Create(71S, 80S, "C"c), _
Tuple.Create(81S, 90S, "B"c), _
Tuple.Create(91S, 100S, "A"c) _
}
' Set custom strings formatting
ReadOnly str_OK As String = "{0}, receives an {1}."
ReadOnly str_FAIL As String = "{0}, unfortunately failed."
ReadOnly str_INCORRECT As String = "{0}, this is an incorrect value. Please try again."
Sub Main()
' Initialize user variables with a default value (0)
Dim anum As Short = 0
Dim name As String = 0
Console.WriteLine("This programme converts marks into grades")
Console.WriteLine("Please enter name...")
name = CStr(Console.ReadLine)
Try
Console.WriteLine("Please enter number of marks...")
anum = CShort(Console.ReadLine())
Catch ex As FormatException
Console.WriteLine("Please enter a valid number...")
Environment.Exit(1) ' Exit from application returning an error exitcode
Catch ex As Exception
Console.WriteLine(String.Format("{0}: {1}", _
ex.Message, _
ex.StackTrace))
Environment.Exit(1) ' Exit from application returning an error exitcode
End Try
Select Case anum
Case Is <= 50
Console.WriteLine(String.Format(str_FAIL, name))
Case Is >= 101
Console.WriteLine(String.Format(str_INCORRECT, name))
Case Else ' User value is inside an accepted range
For Each Item As Tuple(Of Short, Short, Char) In TupleList
If (anum >= Item.Item1 AndAlso anum <= Item.Item2) Then
Console.WriteLine(String.Format(str_OK, name, Item.Item3))
Environment.Exit(0) ' Exit from application
' Exit For
End If
Next Item
End Select
Environment.Exit(1) ' Exit from application returning an error exitcode
' ( When Is <= 50 or Is >= 101 )
End Sub
End Module

Answer 2

The only thing I would do different than your original code is:
Use "Case Else" in place of "Case Is > 100" for your final Case statement.
This way it would handle an error if someone entered something other than a number.
Good work and good luck!