Bug #77655 [NEW]: Long String in Return Value is Empty

From: marc dot ruef at computec dot ch Operating system: Linux Kernel 3.10.0-862.14.4.el7 PHP version: 7.3.2 Package: Strings related Bug Type: Bug Bug description:Long String in Return Value is Empty Description: ------------ I am having a for loop which is iterating through a large array $result. Every array item $row is used to generate a new line of string $line. This string is concatenated into $str. To preserve memory, I am using unset($result[$i]) to clear every array item that has been processed in the original array. This (more or less exotic piece of code) works unless the string exceeds a length of 999'775 characters. In this case the return value is just empty. This is highly irritating because: 1. The calculation effort (in this example do_something()) is not a problem. By using echo count($result).' - '.strlen($str)."\n" I can see that the loop finishes properly. There is no web server or php error shown. 2. The memory_limit is also not a problem. I am working with more data on other parts of the application. It appears that the problem lies in return $str itself. If I am using return substr($str, 0, 980000) then it just works fine. I can't put those exceeding return value strings into another string variable. But I am able to do a strlen() to get a proper result (1310307). But I can't use them properly as a string. Using an `echo $str` in the function works properly. But return doesn't. Test script: --------------- function what_is_going_on($result){ $resultcount = count($result); for($i=0; $i<$resultcount; ++$i){ $row = $result[$i]; $line = do_something($row); $str.= $line; unset($result[$i]); } return $str; } $output = what_is_going_on($result); echo $output; -- Edit bug report at https://bugs.php.net/bug.php?id=77655&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=77655&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=77655&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=77655&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=77655&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=77655&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=77655&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=77655&r=needscript Try newer version: https://bugs.php.net/fix.php?id=77655&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=77655&r=support Expected behavior: https://bugs.php.net/fix.php?id=77655&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=77655&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=77655&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=77655&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=77655&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=77655&r=dst IIS Stability: https://bugs.php.net/fix.php?id=77655&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=77655&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=77655&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=77655&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=77655&r=mysqlcfg