Regression in Date::stringToExcel

Fix PHPOffice#4448.

Author: oleibman

CHANGELOG.md

@@ -31,6 +31,12 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 - Nothing yet.
 
+## 2025-05-26 - 4.3.1
+
+### Fixed
+
+- Regression in Date::stringToExcel. [Issue #4448](https://github.com/PHPOffice/PhpSpreadsheet/issues/4448) [PR #4449](https://github.com/PHPOffice/PhpSpreadsheet/pull/4449)
+
 ## 2025-05-25 - 4.3.0
 
 ### Added

src/PhpSpreadsheet/Shared/Date.php

@@ -471,7 +471,7 @@ public static function stringToExcel(string $dateValue): bool|float
         if (strlen($dateValue) < 2) {
             return false;
         }
-        if (!preg_match('/^(\d{1,4}[ \.\/\-][A-Z]{3,9}([ \.\/\-]\d{1,4})?|[A-Z]{3,9}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?|\d{1,4}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?)( \d{1,2}:\d{1,2}(:\d{1,2}([.]\d+))?)?$/iu', $dateValue)) {
+        if (!preg_match('/^(\d{1,4}[ \.\/\-][A-Z]{3,9}([ \.\/\-]\d{1,4})?|[A-Z]{3,9}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?|\d{1,4}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?)( \d{1,2}:\d{1,2}(:\d{1,2}([.]\d+)?)?)?$/iu', $dateValue)) {
             return false;
         }
 

tests/PhpSpreadsheetTests/Shared/DateTest.php

@@ -189,6 +189,12 @@ public function testVarious(): void
         self::assertTrue((bool) Date::stringToExcel('2019-02-28'));
         self::assertTrue((bool) Date::stringToExcel('2019-02-28 11:18'));
         self::assertFalse(Date::stringToExcel('2019-02-28 11:71'));
+        $timestamp1 = Date::stringToExcel('26.05.2025 14:28:00');
+        $timestamp2 = Date::stringToExcel('26.05.2025 14:28:00.00');
+        self::assertNotFalse($timestamp1);
+        self::assertNotFalse($timestamp2);
+        self::assertEqualsWithDelta($timestamp1, 45803.60277777778, 1.0E-10);
+        self::assertSame($timestamp1, $timestamp2);
 
         $date = Date::PHPToExcel('2020-01-01');
         self::assertEquals(43831.0, $date);