tests passed

Author: jyalim

Doc/library/datetime.rst

@@ -2568,9 +2568,11 @@ requires, and these work on all supported platforms.
 |           |                                || Di 16 Aug 21:30:00    |       |
 |           |                                |  1988 (de_DE)          |       |
 +-----------+--------------------------------+------------------------+-------+
-|  ``%C``   | The year divided by 100 and    | 01, 02, ..., 99        | \(0)  |
+|  ``%C``   | The year divided by 100 and    | 01, 02, ..., 99        |       |
 |           | truncated to an integer as a   |                        |       |
 |           | zero-padded decimal number.    |                        |       |
+|           | For :meth:`!strptime`,         |                        |       |
+|           | zero-padding is not required.  |                        |       |
 +-----------+--------------------------------+------------------------+-------+
 |  ``%d``   | Day of the month as a          | 01, 02, ..., 31        | \(9)  |
 |           | zero-padded decimal number.    |                        |       |

Lib/_strptime.py

@@ -371,9 +371,9 @@ def __init__(self, locale_time=None):
             # W is set below by using 'U'
             'y': r"(?P<y>\d\d)",
             'Y': r"(?P<Y>\d\d\d\d)",
-            # follow C99 specification of only parsing two digits for
+            # follow C99 specification of parsing up to two digits for
             # first hundred centuries
-            'C': r"(?P<C>\d\d)",
+            'C': r"(?P<C>\d{1,2})",
             # See gh-121237: "z" must support colons for backwards compatibility.
             'z': r"(?P<z>([+-]\d\d:?[0-5]\d(:?[0-5]\d(\.\d{1,6})?)?)|(?-i:Z))?",
             ':z': r"(?P<colon_z>([+-]\d\d:[0-5]\d(:[0-5]\d(\.\d{1,6})?)?)|(?-i:Z))?",
@@ -617,6 +617,21 @@ def parse_int(s):
                     year += 2000
                 else:
                     year += 1900
+        elif group_key == 'C' and 'y' not in found_dict:
+            # C99 support for century in [0,99] (years 0-9999).
+            century = parse_int(found_dict[group_key])
+            year = century * 100
+            if century > 0:
+                year = century * 100
+            elif century == 0:
+                # ValueError fix, since MINYEAR = 1 in Lib/_pydatetime.py
+                year = 1
+            else:
+                # in line with other format directives, negative numbers
+                # are not supported by the regular expression; 
+                # this branch will not trigger!
+                msg = f"Negative century unsupported ({found_dict[group_key]})"
+                raise ValueError(msg)
         elif group_key == 'Y':
             year = int(found_dict['Y'])
         elif group_key == 'G':
@@ -627,15 +642,6 @@ def parse_int(s):
             month = locale_time.f_month.index(found_dict['B'].lower())
         elif group_key == 'b':
             month = locale_time.a_month.index(found_dict['b'].lower())
-        elif group_key == 'C' and 'y' not in found_dict:
-            # C99 support for century in [0,99] (years 0-9999).
-            century = parse_int(found_dict[group_key])
-            year = century * 100
-            if century > 0:
-                year = century * 100
-            else:
-                # ValueError fix, since MINYEAR = 1 in Lib/_pydatetime.py
-                year = 1
         elif group_key == 'd':
             day = parse_int(found_dict['d'])
         elif group_key == 'H':

Lib/test/datetimetester.py

@@ -2221,6 +2221,26 @@ def test_strptime_n_and_t_format(self):
                         self.theclass(2026, 2, 3),
                     )
 
+    def test_strptime_C_format(self):
+        # verify cent. 0, zero-padding, modern cent., last supported cent.
+        test_centuries = ('0', '01', '20', '99')
+        for c in test_centuries:
+            expected_year = int(c) * 100 if int(c) != 0 else 1
+            with self.subTest(format_directive="C", century=c):
+                self.assertEqual(
+                    self.theclass.strptime(c, "%C"),
+                    self.theclass(expected_year, 1, 1)
+                )
+
+    def test_strptime_C_y_format(self):
+        # verify %y correctly augmented by century %C
+        test_years = ('0001', '1687', '1991', '2026')
+        for y in test_years:
+            with self.subTest(format_directive="%C%y", year=y):
+                self.assertEqual(
+                    self.theclass.strptime(y, "%C%y"),
+                    self.theclass(int(y), 1, 1)
+                )
 
 #############################################################################
 # datetime tests

Lib/test/test_strptime.py

@@ -687,6 +687,27 @@ def test_strptime_n_and_t_format(self):
                         ),
                     )
 
+    def test_strptime_C_format(self):
+        # verify cent. 0, zero-padding, modern cent., last supported cent.
+        test_centuries = ('0', '01', '20', '99')
+        for c in test_centuries:
+            expected_year = int(c) * 100 if int(c) != 0 else 1
+            with self.subTest(format_directive="C", century=c):
+                self.assertEqual(
+                    time.strptime(c, "%C"),
+                    time.strptime(f'{expected_year:04d}-01-01', '%Y-%m-%d'),
+                )
+
+    def test_strptime_C_y_format(self):
+        # verify %y correctly augmented by century %C
+        test_years = ('0001', '1687', '1991', '2026')
+        for year in test_years:
+            with self.subTest(format_directive="%C%y", year=year):
+                self.assertEqual(
+                    time.strptime(year, '%C%y'),
+                    time.strptime(f'{year}-01-01', '%Y-%m-%d'),
+                )
+
 class Strptime12AMPMTests(unittest.TestCase):
     """Test a _strptime regression in '%I %p' at 12 noon (12 PM)"""
 

Lib/test/test_time.py

@@ -358,8 +358,8 @@ def test_strptime(self):
         # Should be able to go round-trip from strftime to strptime without
         # raising an exception.
         tt = time.gmtime(self.t)
-        for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'D', 'F', 'H', 'I',
-                          'j', 'm', 'M', 'n', 'p', 'S', 't', 'T',
+        for directive in ('a', 'A', 'b', 'B', 'c', 'C', 'd', 'D', 'F', 'H',
+                          'I', 'j', 'm', 'M', 'n', 'p', 'S', 't', 'T',
                           'U', 'w', 'W', 'x', 'X', 'y', 'Y', 'Z', '%'):
             format = '%' + directive
             if directive == 'd':