PHP: fwrite - Manual

Description

int fwrite ( resource handle, string string [, int length])

fwrite() writes the contents of string to the file stream pointed to by handle. If the length argument is given, writing will stop after length bytes have been written or the end of string is reached, whichever comes first.

fwrite() returns the number of bytes written, or FALSE on error.

Note that if the length argument is given, then the magic_quotes_runtime configuration option will be ignored and no slashes will be stripped from string.

Notã: On systems which differentiate between binary and text files (i.e. Windows) the file must be opened with 'b' included in fopen() mode parameter.

Exemplu 1. A simple fwrite example
<?php $filename = 'test.txt'; $somecontent = "Add this to the file\n"; // Let's make sure the file exists and is writable first. if (is_writable($filename)) { // In our example we're opening $filename in append mode. // The file pointer is at the bottom of the file hence // that's where $somecontent will go when we fwrite() it. if (!$handle = fopen($filename, 'a')) { print "Cannot open file ($filename)"; exit; } // Write $somecontent to our opened file. if (!fwrite($handle, $somecontent)) { print "Cannot write to file ($filename)"; exit; } print "Success, wrote ($somecontent) to file ($filename)"; fclose($handle); } else { print "The file $filename is not writable"; } ?>

add a note User Contributed Notes
fwrite

php at biggerthanthebeatles dot com
21-Aug-2003 08:04


Hope this helps other newbies.



If you are writing data to a txt file on a windows system and need a line break. use \r\n . This will write hex OD OA.



i.e.

$batch_data= "some data... \r\n";

fwrite($fbatch,$batch_data);



The is the equivalent of opening a txt file in notepad pressing enter and the end of the line and saving it.

Andi
17-Jul-2003 07:32


I figured out problems when writing to a file using \r as linebreak, after that file() wasn't able to read the data from that file.

Using \n solved the problem.

chedong at hotmail dot com
20-Jun-2003 07:36


the fwrite output striped the slashes if without length argument given, example:



<?php

$str = "c:\\01.txt";

$out = fopen("out.txt", "w");

fwrite($out, $str);

fclose($out);

?>



the out.txt will be:

c:^@1.txt

the '\\0' without escape will be '\0' ==> 0x00.



the correct one is change fwrite to:

fwrite($out, $str, strlen($str));

Jake Roberts
04-Jun-2003 04:35


Use caution when using:



$content = fread($fh, filesize($fh)) or die "Error Reading";



This will cause an error if the file you are reading is zero length.



Intead use:



if ( false === fread($fh, filesize($fh)) ) die "Error Reading";



Thus it will be successful on reading zero bytes but detect and error returned as FALSE.

Chris Blown
19-May-2003 08:12


Don't forget to check fwrite returns for errors! Just because you successfully opened a file for write, doesn't always mean you can write to it.  



On some systems this can occur if the filesystem is full, you can still open the file and create the filesystem inode, but the fwrite will fail, resulting in a zero byte file.

seeker at seek dot planet
10-Feb-2003 03:33


[[Editors note: There is no "prepend" mode, you must essentially rewrite the entire file after prepending contents to a string. Perhaps you will use file(), modify, implode(), then fopen()/fwrite() it back]]


To put strings into the front of the file, you need to set place the pointer at the top of the file when openning the file with fopen(), see fopen() for more info.

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