Doc #75136 [Nab]: readdir is returning null.

Edit report at https://bugs.php.net/bug.php?id=75136&edit=1 ID: 75136 Updated by: requinix@php.net Reported by: dmitriy dot vinograd at gmail dot com Summary: readdir is returning null. Status: Not a bug Type: Documentation Problem Package: Documentation problem Operating System: Ubuntu 16.04.3 LTS PHP Version: 7.0.22 Block user comment: N Private report: N New Comment: To add to that, > I suppose an author was encouraged by the example from the documentation The author apparently forgot about operator precedence. && has higher precedence than = [1] so the code is effectively if ($dir = (opendir($filePath) && is_numeric($noOfDays) > 0)) which means yes, the code never worked correctly to begin with. You can also quickly infer from this that readdir() is being passed true - not false. Use "and" or parentheses. https://3v4l.org/so2bX Perhaps the is_numeric() check was just added? Speaking of, the author of that piece apparently forgot that is_numeric returns bool, so comparing >0 is nonsensical although functional. [1] http://php.net/manual/en/language.operators.precedence.php Meanwhile the "which evaluates to FALSE" note is a macro which typically means the function can also return 0 or an empty string. Since readdir() does not return integers and it's not possible to have a file/directory named "" (as far as I know) the warning would be alluding to the string "0". Side comment: opendir/readdir/closedir loops are old. scandir and glob are easier. Previous Comments: ------------------------------------------------------------------------ [2017-08-30 13:40:30] salathe@php.net Closing as not a bug for the readdir() page. Returning NULL is a convention widely used throughout PHP and is not something we document for every individual function. " Note: If the parameters given to a function are not what it expects, such as passing an array where a string is expected, the return value of the function is undefined. In this case it will likely return NULL but this is just a convention, and cannot be relied upon." -- http://php.net/manual/en/functions.internal.php ------------------------------------------------------------------------ [2017-08-30 13:22:20] spam2 at rhsoft dot net what makes YOU think NULL is the correct return in case of a invalid param when the doc says it returns boolean flase when not sucessful anyways, that's why i ported a 250000 LOC codebase in the last year to declare(strict_types=1); which would lead to a exception in the case below ------------------------------------------------------------------------ [2017-08-30 13:20:11] dmitriy dot vinograd at gmail dot com // The documentation actually alerts you that this is a possible return value. Quoting: Yes, you are absolutely right. Despite the fact, I still don't see any reasons why the function is returning null in this case. Also, I would like to add that mentioned code wasn't implemented by me and I suppose an author was encouraged by the example from the documentation. Also, I personally believe that this is a pretty hard to predict consequences from this warning message. ------------------------------------------------------------------------ [2017-08-30 13:08:51] dmitriy dot vinograd at gmail dot com //What makes you think false is a valid argument for the function? Nothing we even have a check in our code to pretend it, but when you have a lot of processes there is still a chance that it happens in between. Which may occur with our site yesterday, if ($dir = opendir($filePath) && is_numeric($noOfDays) > 0) { while (false !== ($logFile = readdir($dir))) ------------------------------------------------------------------------ [2017-08-30 13:01:37] mail at pmmaga dot net The documentation actually alerts you that this is a possible return value. Quoting: Warning This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=75136 -- Edit this bug report at https://bugs.php.net/bug.php?id=75136&edit=1