For my program, valid standard time formats look like this:

1:59 am
159am
159 AM
1:59 PM

I created the following code to convert the above types of
formats into military times. Does anyone know if this code
can be improved or simplified? I prefer to do time conversions
as quickly as possible. Maybe someone has a better
technique than mine?

Here is the code:
'----------------------------------------------------------
Dim reg As New VBScript_RegExp_55.RegExp
Dim sentence As String
Dim tHours As String
Dim tMins As String
Dim tMeridiem As String
Dim militaryHour As String
Dim match, matches

sentence = "6:59 pm" ' Example input time

reg.Pattern = "^\s*(1[012]|[1-9]):?([0-5][0-9])\s*(am|pm)$"
reg.IgnoreCase = True
reg.Global = True

' Check if format is valid
If reg.Test(sentence) Then
Set matches = reg.Execute(sentence)
Set match = matches(0)

tHours = match.SubMatches(0)
tMins = match.SubMatches(1)
tMeridiem = match.SubMatches(2)

If (tHours = "12") Then
' Handle midnight and noon cases
If (tMeridiem = "am") Then
militaryHour = "00"
Else
militaryHour = "12"
End If
Else
If (tMeridiem = "am") Then
militaryHour = tHours
Else
militaryHour = CStr(Val(tHours) + 12)
End If
If (Val(militaryHour) < 10) Then
militaryHour = "0" + militaryHour
End If
End If
MsgBox "Military time: " + militaryHour + tMins
Else
MsgBox "Invalid format time string"
End If