Title: Find palindrome dates in Python

A palindrome date is a date that, in numeric format, reads the same forward and backward. For example, 12/1/21.

To find the most dates, you can consider all formats including two-digit days and four-digit years, and you can ignore the separator characters. For example, 5/20/2025 is a palindrome because 5202025 is the same forward and backward. (May 2025 has a whopping 12 palindrome dates in the m/d/y format!)

Obviously this depends on whether you use the m/d/y, d/m/y, or y/m/d format. It also depends on whether you use one- or two-digit month and day numbers, and whether you use two- or four-digit years so all of these combinations are possible in m/d/y format: 05/05/25, 5/05/25, 05/5/25, 05/05/2025, 5/05/2025, and 05/5/2025. For this program, I'm going to assume that the month and day values either both use one-digit values or both use two-digit values.

When you click the Go button, the program uses the following code to search for palindrome dates.

def go_click(self): # Get the selected date format. # Unix version (untested): match self.format_var.get(): case 0: # m/d/y formats. formats = [ '%m/%d/%y', '%-m/%-d/%y', '%m/%d/%Y', '%-m/%-d/%Y', ] case 1: # d/m/y formats. formats = [ '%d/%m/%y', '%-d/%-m/%y', '%d/%m/%Y', '%-d/%-m/%Y', ] case 2: # y/m/d formats. formats = [ '%y/%d/%m', '%y/%-d/%-m', '%Y/%d/%m', '%Y/%-d/%-m', ] # Windows version: match self.format_var.get(): case 0: # m/d/y formats. formats = [ '%m/%d/%y', '%#m/%#d/%y', '%m/%d/%Y', '%#m/%#d/%Y', ] case 1: # d/m/y formats. formats = [ '%d/%m/%y', '%#d/%#m/%y', '%d/%m/%Y', '%#d/%#m/%Y', ] case 2: # y/m/d formats. formats = [ '%y/%d/%m', '%y/%#d/%#m', '%Y/%d/%m', '%Y/%#d/%#m', ] # Start with an empty list or results. palindromes = [] # Build the list of dates. self.results_treeview.delete(*self.results_treeview.get_children()) date = datetime.strptime(self.start_date_var.get(), '%Y-%m-%d') end_date = datetime.strptime(self.end_date_var.get(), '%Y-%m-%d') while date <= end_date: for format in formats: date_string = date.strftime(format) without_slashes = date_string.replace('/', '') # Skip it if is already in the list. if without_slashes in palindromes: continue # See if it is a palindrome. is_palindrome = without_slashes == without_slashes[::-1] if is_palindrome: print(without_slashes) self.results_treeview.insert('', tk.END, values=(f'{without_slashes}', f'({date_string})')) date += dt.timedelta(days=1)

Next, the program loops through the dates that you entered. For each date, it loops through the formats. It uses the format to convert the date into a string, removes the slashes from the string, and then uses string slicing to determine whether the result is a palindrome. If the date is a palindrome, the program adds the date with and without slashes to the results_treeview widget.

Download the example to see additional details.