VB.Net/Language Basics/Integer Parser

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Validate an Integer

<source lang="vbnet"> Imports System Public Class MainClass

   Shared Sub Main(ByVal args As String())
       Dim num_items As Integer
       If Not IsValidInteger(num_items, "00", 1, 100) Then Exit Sub
       
   End Sub
   Shared     Private Function IsValidInteger(ByRef result As Integer, _
   ByVal txt As String, ByVal field_name As String, _
   Optional ByVal min_value As Integer = Integer.MinValue, _
   Optional ByVal max_value As Integer = Integer.MaxValue) As Boolean
       " Check for blank entry.
       If txt.Length < 1 Then
           Console.WriteLine("Please enter " & field_name & ".")
           Return False
       End If
       " See if it"s numeric.
       If Not IsNumeric(txt) Then
           Console.WriteLine(field_name & " must be a number.")
           Return False
       End If
       " Assign the value.
       Try
           result = Integer.Parse(txt)
       Catch ex As Exception
           Console.WriteLine("Error in " & field_name & "." & _
           vbCrLf & ex.Message)
           Return False
       End Try
       " Check that the value is between min_value and max_value.
       If result < min_value Or result > max_value Then
           Console.WriteLine(field_name & " must be between " & _
           min_value.ToString & " and " & max_value.ToString & ".")
           Return False
       End If
       " The value is okay.
       Return True
   End Function

End Class

      </source>