#28371 [Opn]: Different behaviour of fopen depending on r+,w+,a+

ID: 28371 User updated by: rc at opelgt dot org Reported By: rc at opelgt dot org Status: Open Bug Type: Filesystem function related Operating System: MacOSX 10.3 PHP Version: 4.3.4 New Comment: I think it could be mention in the manual: In PHP 4.2.3 the read pointer for fopen with 'a' is at the end of file. Instead in 4.3.4 the pointer is at '0'! So rewind for reading in 4.3.4 with 'a+' is no longer nessessary. Rüdiger Previous Comments: ------------------------------------------------------------------------ [2004-05-12 19:12:34] rc at opelgt dot org Do you really think when such strange differences occur and the fopen description says nothing about it, its a question for support? Do you know why this differences occurs? Output with w+ is: Inhalt<BR> alt: <BR> neu: and with r+: Inhalt<BR> alt: 1234567890<BR> neu: Rüdiger ------------------------------------------------------------------------ [2004-05-12 18:52:46] wez@php.net The output under both linux and OSX is: Inhalt<BR> alt: 1234567890<BR> neu: 13579 Your bug report doesn't sound so much like a bug report, but a support request; this isn't a support forum, so if you don't understand these results even after careful scrutiny of the fopen() manual page, please visit http://www.php.net/support.php to find someone who might be able to help you. ------------------------------------------------------------------------ [2004-05-12 17:20:59] rc at opelgt dot org Description: ------------ Hello, for my skill its a bit too much to understand whats going on here. Reproduce code: --------------- <?php $alt = '1234567890'; $neu = '13579'; $datei = 'test.txt'; $dh = fopen ($datei,"w"); fwrite($dh, $alt); fclose($dh); // pos1 $dh = fopen ($datei,"a+"); // just alter the mode to test others rewind($dh); echo "Inhalt<BR>\nalt: ".fread($dh, filesize($datei))."<BR>\n"; ftruncate($dh, '0'); fwrite($dh, $neu); rewind($dh); echo 'neu: '.fread($dh, filesize($datei)); fclose($dh); ?> Expected result: ---------------- I wrote the code above and exspected same behaviour for r+, w+ and a+. Before pos1 The content of 'test.txt' is written to '1234567890'. After pos1 the file is opened anothertime with r+,w+ or a+. Rewind sets the pointer to '0'. So that fread can read the file from the beginning. Ftruncate makes the size of the file to '0' and sets the pointer to the beginning of the file. Fwrite writes the new content and the size of the file will be as big as nessessary for the content. Rewind takes the pointer back from end to beginning of the file. Actual result: -------------- Echo should tell the new content. This only works with a+, but with r+ and w+ nothing is displayed. The first echo command tells the 'old' content in a+ and r+ mode, but not with w+. Seems to me there are undocumented differences between the modes that makes it difficult to choose and use one of them. Rüdiger ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=28371&edit=1