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
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