Is there a way to maintain the length of a user entered number, to prevent removal of extra 0's? - vb.net

Question

I'm creating a Diabetes management algorithm, and I'm trying to find a way for the user's entered time blocks to be maintained at 4 digits
I've been searching on google, but all I have been able to find is how to check the length of a variable, which I already know how to do.
Sub timeBlocks()
Dim file As String = "C:\Users\Connor\Documents\Visual Studio 2017\Projects\meterCodeMaybe\TIMEBLOCKS.txt"
Dim blockNum As Integer
Console.WriteLine("Please be sure to enter times as a 24 hour value, rather than 12 hour, otherwise the input will not be handled.")
Console.Write("Please enter the amount of time blocks you require for your day: ")
blockNum = Console.ReadLine()
Dim timeA(blockNum - 1) As Integer
Dim timeB(blockNum - 1) As Integer
Dim sensitivity(blockNum - 1) As Integer
Dim ratio(blockNum - 1) As Integer
For i = 0 To (blockNum - 1)
Console.WriteLine("Please enter the start time of your time block")
timeA(i) = Console.ReadLine()
Console.WriteLine("Please enter the end time of your time block")
timeB(i) = Console.ReadLine()
Console.WriteLine("Please enter the ratio for this time block (Enter the amount of carbs that go into 1 unit of insulin)")
ratio(i) = Console.ReadLine()
Console.WriteLine("Please enter the insulin sensitivity for this time block
(amount of blood glucose (mmol/L) that is reduced by 1 unit of insulin.)")
sensitivity(i) = Console.ReadLine()
FileOpen(1, file, OpenMode.Append)
PrintLine(1, Convert.ToString(timeA(i)) + "-" + Convert.ToString(timeB(i)) + " 1:" + Convert.ToString(ratio(i)) + " Insulin Sensitivity:" + Convert.ToString(sensitivity(i)) + " per mmol/L")
FileClose(1)
Next
End Sub
Basically, I want the user to be able to enter a 4 digit number for their time block, to match a 24 hr time, so if they enter 0000, it is displayed as this, however, it removes all previous 0's and sets it to just 0.

Answer 1

Perhaps pad the number with 4 leading 0's:
Right(String(digits, "0") & timeA(i), 4)
Or as an alternative, store the value as a string so that it can be printed out in its original form.

Answer 2

I have written a Function to get a 24 hours format time from user, I hope it would help:
Public Function Read24HFormatTime() As String
Dim str As String = String.Empty
While True
Dim c As Char = Console.ReadKey(True).KeyChar
If c = vbCr Then Exit While
If c = vbBack Then
If str <> "" Then
str = str.Substring(0, str.Length - 1)
Console.Write(vbBack & " " & vbBack)
End If
ElseIf str.Length < 5 Then
If Char.IsDigit(c) OrElse c = ":" Then
If str.Length = 0 Then
' allow 0, 1 or 2 only
If c = "0" OrElse c = "1" OrElse c = "2" Then
Console.Write(c)
str += c
End If
ElseIf str.Length = 1 Then
If str = "0" Then
'allow 1 to 9
If c <> ":" Then
If CInt(c.ToString) >= 1 AndAlso CInt(c.ToString) <= 9 Then
Console.Write(c)
str += c
End If
End If
ElseIf str = "1" Then
'allow 0 to 9
If c <> ":" Then
If CInt(c.ToString) >= 0 AndAlso CInt(c.ToString) <= 9 Then
Console.Write(c)
str += c
End If
End If
ElseIf str = "2" Then
'allow 0 to 4
If c <> ":" Then
If CInt(c.ToString) >= 0 AndAlso CInt(c.ToString) <= 4 Then
Console.Write(c)
str += c
End If
End If
End If
ElseIf str.Length = 2 Then
'allow ":" only
If c = ":" Then
Console.Write(c)
str += c
End If
ElseIf str.Length = 3 Then
If str = "24:" Then
'allow 0 only
If c = "0" Then
Console.Write(c)
str += c
End If
Else
'allow 0 to 5
If c <> ":" Then
If CInt(c.ToString) >= 0 AndAlso CInt(c.ToString) <= 5 Then
Console.Write(c)
str += c
End If
End If
End If
ElseIf str.Length = 4 Then
If str.Substring(0, 3) = "24:" Then
'allow 0 only
If c = "0" Then
Console.Write(c)
str += c
End If
Else
'allow 0 to 9
If c <> ":" Then
If CInt(c.ToString) >= 0 AndAlso CInt(c.ToString) <= 9 Then
Console.Write(c)
str += c
End If
End If
End If
End If
End If
End If
End While
Return str
End Function
The user can only enter time like 23:59 08:15 13:10 and he couldn't enter formats like 35:10 90:00 25:13 10:61
This is a sample code to show you how to use it:
Dim myTime = DateTime.Parse(Read24HFormatTime())
Dim name = "Emplyee"
Console.WriteLine($"{vbCrLf}Hello, {name}, at {myTime:t}")
Console.ReadKey(True)