Bug #81651 [NEW]: In a for loop using dates, a date modify also updates the initial variable

From: cliffie dot baker at gmail dot com Operating system: Windows 10 PHP version: 7.4.26 Package: Date/time related Bug Type: Bug Bug description:In a for loop using dates, a date modify also updates the initial variable Description: ------------ Using a for loop to generate a range of dates and using the date modify to do the increment, the initial variable used for the start date is also being updated. I don't think this is the correct behaviour and certainly isn't consistent with a simple for loop. Must admit I haven't tested in PHP 7.4.26 but have in 7.4.25 Tested using the 7.4.25 version of Xampp environment and also the 'try it' feature of the w3schools Test script: --------------- $start_date = new datetime('first Monday of January 2022'); $end_date = new datetime('last Monday of January 2022'); for ($date1 = $start_date; $date1 <= $end_date; $date1->modify('+1 week')) { echo $date1->format('Y-m-d').'<br>'; } echo 'Start date '. $start_date->format ('Y-m-d'); Gives 2022-01-03 2022-01-10 2022-01-17 2022-01-24 2022-01-31 Start date 2022-02-07 The original start date of 2022-01-03 has been updated to 2022-02-07 through the loop Compare this to a simple for loop $start = 5; for ($x = $start; $x <= 10; $x++) { echo "The number is: $x <br>"; } echo 'start '.$start; ?> Gives The number is: 5 The number is: 6 The number is: 7 The number is: 8 The number is: 9 The number is: 10 start 5 This is as expected Expected result: ---------------- Should be - For a for loop with date modify Start 2022-01-03 (the original value) Actual result: -------------- Actual For a for loop with date modify Start date 2022-02-07 (the updated value at the end of the loop) -- Edit bug report at https://bugs.php.net/bug.php?id=81651&edit=1 -- Fix committed: https://bugs.php.net/fix.php?id=81651&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=81651&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=81651&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=81651&r=needscript Try newer version: https://bugs.php.net/fix.php?id=81651&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=81651&r=support Expected behavior: https://bugs.php.net/fix.php?id=81651&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=81651&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=81651&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=81651&r=globals PHP version support discontinued: https://bugs.php.net/fix.php?id=81651&r=phptooold Daylight Savings: https://bugs.php.net/fix.php?id=81651&r=dst IIS Stability: https://bugs.php.net/fix.php?id=81651&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=81651&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=81651&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=81651&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=81651&r=mysqlcfg