Imports System
Imports System.Text.RegularExpressions
Module Module1
Sub Main()
'
' This regex matches ONLY the first 28 days of any month.
'
' Explanation:
' ---------------------------------------------------------
' (0[1-9] | 1[0-9] | 2[0-8])
' → Matches days 01–28
'
' [-\/]
' → Allows either "-" or "/" as the date separator
'
' (0[1-9] | 1[0-2])
' → Matches months 01–12
'
' \d{4}
' → Matches a 4‑digit year
'
' ^ and $
' → Ensure the entire string is a valid date format
'
Dim pattern As String = "^(0[1-9]|1[0-9]|2[0-8])[-\/](0[1-9]|1[0-2])[-\/]\d{4}$"
Dim regex As New Regex(pattern)
Dim testDates() As String = {
"01/01/2024", ' valid
"15-05-2023", ' valid
"28/12/2022", ' valid
"29/02/2024", ' invalid (29th)
"30/07/2024", ' invalid
"31/01/2024", ' invalid
"05/13/2024" ' invalid month
}
For Each d In testDates
Dim isMatch As Boolean = regex.IsMatch(d)
Console.WriteLine($"{d} → {(If(isMatch, "MATCH", "NO MATCH"))}")
Next
End Sub
End Module
' run:
'
' 01/01/2024 → MATCH
' 15-05-2023 → MATCH
' 28/12/2022 → MATCH
' 29/02/2024 → NO MATCH
' 30/07/2024 → NO MATCH
' 31/01/2024 → NO MATCH
' 05/13/2024 → NO MATCH
'
