Bug #76624 [Opn->Nab]: date_create_from_format doesn't respect "T" Timezone format character

Edit report at https://bugs.php.net/bug.php?id=76624&edit=1 ID: 76624 Updated by: requinix@php.net Reported by: jalaj dot chhalotre at gmail dot com Summary: date_create_from_format doesn't respect "T" Timezone format character -Status: Open +Status: Not a bug Type: Bug Package: Date/time related Operating System: Ubuntu 16.04.1 PHP Version: 7.0.30 Block user comment: N Private report: N New Comment: Well spotted, @a. Indeed, there are three different "IST" timezones. Abbreviations are not unique. https://en.wikipedia.org/wiki/List_of_time_zone_abbreviations Previous Comments: ------------------------------------------------------------------------ [2018-07-15 09:56:45] a at b dot c dot de What timezone does IST name? Jerusalem, Kolkata, or Dublin? <?php $date2=date_create_from_format('Y-m-d H:i:s T', '2018-07-13 15:30:15 IST'); echo $date2->format('Y-m-d H:i:s e (T)'),"\t", $date2->format('U'),"\n"; echo "\n"; foreach(array_column(DateTimeZone::listAbbreviations()['ist'], 'timezone_id') as $tz) { $date1 = new DateTime('2018-07-13 15:30:15', new DateTimeZone($tz)); echo $date1->format('Y-m-d H:i:s e (T)'),"\t", $date1->format('U'),"\n"; } Apparently it's interpreted as Israel Standard Time. Suggest you avoid the ambiguity and stick with using "Asia/Kolkata". $date2=date_create_from_format('Y-m-d H:i:s T', '2018-07-13 15:30:15 Asia/Kolkata'); echo $date2->format('Y-m-d H:i:s e (T)'),"\t", $date2->format('U'),"\n"; ------------------------------------------------------------------------ [2018-07-15 08:07:00] jalaj dot chhalotre at gmail dot com Noticed this bug is timezone dependent, e.g. if TimeZone is CDT (Canada/Central) the difference in epoch of mentioned function is 0. On the other side IST, CST(China Standard time) result in epoch difference. Created a test function to check variability of this bug with timezone. <?php bug_epoch_diff('2018-07-13 15:30:15','Asia/Shanghai'); bug_epoch_diff('2018-07-13 15:30:15','Asia/Kolkata'); bug_epoch_diff('2018-07-13 15:30:15','Asia/Hong_Kong'); bug_epoch_diff('2018-07-13 15:30:15','Asia/Macau'); bug_epoch_diff('2018-07-13 15:30:15','Asia/Macau'); bug_epoch_diff('2018-07-13 15:30:15','Canada/Central'); bug_epoch_diff('2018-07-13 15:30:15','Brazil/Acre'); bug_epoch_diff('2018-07-13 15:30:15','Europe/Berlin'); function bug_epoch_diff($datetime,$timezone){ // date='2018-07-13 15:30:15' TimeZone='Asia/Kolkata' $date = new DateTime($datetime, new DateTimeZone($timezone)); echo "DateTime in format 'Y-m-d H:i:s T': ". $date->format('Y-m-d H:i:s T'); echo " | "; echo $ep1=$date->format('U'); echo " | "; //1531476015 echo $ep2=date_create_from_format('Y-m-d H:i:s T', $date->format('Y-m-d H:i:s T'))->format('U'); //1531488615 echo " | "; //Comment: for same date two different epoch echo "Epoch difference for ".$timezone."=".(((float)$ep2)-((float)$ep1))."<br>"; } ?> _____ Output: DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 CST | 1531467015 | 1531517415 | Epoch difference for Asia/Shanghai=50400 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 IST | 1531476015 | 1531488615 | Epoch difference for Asia/Kolkata=12600 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 HKT | 1531467015 | 1531467015 | Epoch difference for Asia/Hong_Kong=0 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 CST | 1531467015 | 1531517415 | Epoch difference for Asia/Macau=50400 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 CST | 1531467015 | 1531517415 | Epoch difference for Asia/Macau=50400 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 CDT | 1531513815 | 1531513815 | Epoch difference for Canada/Central=0 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 -05 | 1531513815 | 1531513815 | Epoch difference for Brazil/Acre=0 DateTime in format 'Y-m-d H:i:s T': 2018-07-13 15:30:15 CEST | 1531488615 | 1531488615 | Epoch difference for Europe/Berlin=0 ------------------------------------------------------------------------ [2018-07-14 20:43:14] jalaj dot chhalotre at gmail dot com Corrected OS (typo) ------------------------------------------------------------------------ [2018-07-14 20:39:49] jalaj dot chhalotre at gmail dot com Description: ------------ When T timezone format character is used to specify timezone in date_create_from_format() function, wrong time (with respect to epoch) is generated. In test script attached, two different epoch times are generated if 'T' and 'e' timezone format characters are used. However using e format character returns correct time. Test script: --------------- # date_string = "2018-07-13 15:30:15 IST" = "2018-07-13 15:30:15 Asia/Kolkata" $date1 = new DateTime('2018-07-13 15:30:15', new DateTimeZone('Asia/Kolkata')); echo $date1->format('Y-m-d H:i:s T'); //2018-07-13 15:30:15 IST echo $str1=$date1->format('U'); //1531476015 $date2=date_create_from_format('Y-m-d H:i:s T', '2018-07-13 15:30:15 IST'); echo $str2=$date2->format('U'); //1531488615 /* $str1 IS NOT equal to $str2 but date1=date2 */ echo $date1->format('Y-m-d H:i:s e'); //2018-07-13 15:30:15 Asia/Kolkata echo $str3=$date1->format('U'); //1531476015 $date2=date_create_from_format('Y-m-d H:i:s e', '2018-07-13 15:30:15 Asia/Kolkata'); echo $str4=$date2->format('U'); //1531476015 /* $str3 IS equal to $str4 as date1=date3 */ ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76624&edit=1