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PHP : Function Reference : Filesystem Functions : fwrite

fwrite

Binary-safe file write (PHP 4, PHP 5)
int fwrite ( resource handle, string string [, int length] )

fwrite() writes the contents of string to the file stream pointed to by handle.

Parameters

handle

A file system pointer resource that is typically created using fopen().

string

The string that is to be written.

length

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.

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.

Return Values

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

Notes

Note:

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

Note:

If handle was fopen()ed in append mode, fwrite()s are atomic (unless the size of string exceeds the filesystem's block size, on some platforms, and as long as the file is on a local filesystem). That is, there is no need to flock() a resource before calling fwrite(); all of the data will be written without interruption.

Examples

Example651.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($filename, 'a')) {
echo
"Cannot open file ($filename)";
exit;
}

// Write $somecontent to our opened file.
if (fwrite($handle, $somecontent) === FALSE) {
echo
"Cannot write to file ($filename)";
exit;
}

echo
"Success, wrote ($somecontent) to file ($filename)";

fclose($handle);

} else {
echo
"The file $filename is not writable";
}
?>


Related Examples ( Source code ) » fwrite












Code Examples / Notes » fwrite

seeker

[[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.


bahatest

[Editor's Note: No, you only need to use this if you want a BOM (Byte order mark) added to the document - most people do not.]
if you have to write a file in UTF-8 format, you have to add an header to the file like this :
<?php
$f=fopen("test.txt", "wb");
$text=utf8_encode("éaè!");
// adding header
$text="\xEF\xBB\xBF".$text;
fputs($f, $text);
fclose($f);
?>


andi

[Ed. Note:
The runtime configuration setting auto_detect_line_endings should solve this problem when set to On.]
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.


bluevd

Watch out for mistakes in writting a simple code for a hit counter:
<?php
$cont=fopen('cont.txt','r');
$incr=fgets($cont);
//echo $incr;
$incr++;
fclose($cont);
$cont=fopen('cont.txt','a');
fwrite($cont,$incr);
fclose($cont);
?>
Why? notice the second fopen -> $cont=fopen('cont.txt','a');
it opens the file in writting mode (a). And when it ads the incremented
value ( $incr ) it ads it ALONG the old value... so opening the counter
page about 5 times will make your hits number look like this
012131214121312151.21312141213E+ .... you get the piont.
nasty, isn't it? REMEMBER to open the file with the 'w' mode (truncate
the file to 0). Doing this will clear the file content and it will make sure that
your counter works nice. This is the final code
<?php
$cont=fopen('cont.txt','r');
$incr=fgets($cont);
//echo $incr;
$incr++;
fclose($cont);
$cont=fopen('cont.txt','w');
fwrite($cont,$incr);
fclose($cont);
?>
Notice that this work fine =)
XU (alias Iscu Andrei)


will

Using fwrite to write to a file in your include folder...
PHP does not recognise the permissions setting for the file until you restart the server... this script works fine. (still have to create the blank text file first though...it is not created automatically) On OS X Server..
Using the 1 in fopen tells php to look for the file in your include folder. Change your include folder by altering include_path in php.ini
On OS X Server, php.ini is in private/etc/php.ini.default
copy the file and call it php.ini
the default include path is usr/lib/php
(All these folders are hidden - use TinkerTool to reveal them)
<?php
$file = fopen('textfile.txt', 'a', 1);
$text="\n Your text to write \n ".date('d')."-".date('m')."-".date('Y')."\n\n";
fwrite($file, $text);
fclose($file);
?>


zaccraven

Use this to get a UTF-8 Unicode CSV file that opens properly in Excel:
$tmp = chr(255).chr(254).mb_convert_encoding( $tmp, 'UTF-16LE', 'UTF-8');
$write = fwrite( $filepath, $tmp );
Use a tab character, not comma, to seperate the fields in  the $tmp.
Credit for this goes to someone called Eugene Murai, I found this solution by him after searching for several hours.


jake roberts

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.


santibari

To write a specific byte into a file (let's,say 0000 0001), use the function chr().
<?php
fputs($fp,chr(0x01),1);
?>


albert;cutthis;

To write 'true binary' files combine with pack() :
$a = 65530;
$fp = fopen('test.dat', 'w');
fwrite($fp, pack('L', $a));
fclose($fp);


chaobreederxl

This is a simple function I wrote that uses the fopen and fwrite functions to log the actions of users... very useful for tracking your members on your site.
<?php
function loguser($reason,$ext = "db"){
 if(!is_dir("logs")):
  mkdir("logs","0493");
endif;
 $fp = fopen("logs/".date("m-d-y").".".$ext, "a+");
  fwrite($fp, "<strong>".date("g:i:s A")."</strong>: ".$reason."<br/>");
}
?>
To use this, just call the function like so:
<? loguser($_SERVER["REMOTE_ADDR"]." attempted to create another account.","html"); ?>
The second parameter can be changed to anything that would support HTML. If you leave out the second extension, then it automatically uses the .db extension, which works excellent for me.
Hope this helps.
Paul


chedong

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));


chad 0x40 herballure 0x2e com

Remember to check the return value of fwrite(). In particular, writing into a socket can return fewer bytes than requested, and you'll have to try again with the remainder of your data.

chill

In PHP 4.3.7 fwrite returns 0 rather than false on failure.
The following example will output "SUCCESS: 0 bytes written" for existing file test.txt:
$fp = fopen("test.txt", "rw");
if (($bytes_written = fwrite($fp, "This is a test")) === false) {
 echo "Unable to write to test.txt\n\n";
} else {
 echo "SUCCESS: $bytes_written bytes written\n\n";
}


sheyh

if you want to create quickly and without fopen use system, exec
system('echo "blahblah" > /path/file');


kzevian

I needed to append, but I needed to write on the file's beginning, and after some hours of effort this worked for me:
$file = "file.txt";
if (!file_exists("file.txt")) touch("file.txt");
$fh = fopen("file.txt", "r");
$fcontent = fread($fh, filesize("file.txt"));
$towrite = "$newcontent $fcontent";
$fh22 = fopen('file.txt', 'w+');
fwrite($fh2, $towrite);
fclose($fh);
fclose($fh2);


james

I could'nt quite get MKP Dev hit counter to work.... this is how I modified it
<?
function hitcount()
{
$file = "counter.txt";
if ( !file_exists($file)){
       touch ($file);
       $handle = fopen ($file, 'r+'); // Let's open for read and write
       $count = 0;
}
else{
       $handle = fopen ($file, 'r+'); // Let's open for read and write
       $count = fread ($handle, filesize ($file));
       settype ($count,"integer");
}
rewind ($handle); // Go back to the beginning
/*
* Note that we don't have problems with 9 being fewer characters than
 * 10 because we are always incrementing, so we will always write at
  * least as many characters as we read
   **/
fwrite ($handle, ++$count); // Don't forget to increment the counter
fclose ($handle); // Done
return $count;
}      
?>


php

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.


cutmaster

For those who, like me, lost a lot of minutes (hours) to understand why fwrite doesn't create a real utf-8 file, here's the explanation I've found :
I tried to do something like this :
<?php
$myString = utf8_encode("Test with accents éèàç");
$fh=fopen('test.xml',"w");
fwrite($fh,$myString);
fclose($fh);
?>
For a mysterious reason, the resulted file shows the accent without the utf-8 conversion.
I tried the binary, mode, etc. etc. And finally I've found it :
It seems that fwrite NEEDS to have the utf8_encode function INSIDE its parameters like this, to understand it must create a non-text only file :
<?php
$myString = "Test with accents éèàç";
$fh=fopen('test.xml',"w");
fwrite($fh,utf8_encode($myString));
fclose($fh);
?>
Hope this will help


chris blown

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.


goodwork

difficulty appending to file in SAFE MODE ON
if you are getting resource errors etc try this...
$textline="whatever string you submitted or created";
$filename="afilename.log"; // or whatever your path and filename
if (!$handle = fopen($filename, 'a')) {
        echo "Cannot open file ($filename)"; // or handle your error
        exit; }
$textline.="\n"; // dont forget that period
// now write content to our opened file.
IF (fwrite($handle,$textline) === FALSE)
{echo "Cannot write to file ($filename)";// or handle your error
      exit;}
    echo "Success, wrote ($textline) to file ($filename)";
fclose($handle);


mkp dev

bluevd at gmail dot com mentioned a hit counter. In his/her implementation, the file is first opened, read, closed, then opened +truncated, then written, and closed again. An alternative to this is:
<?php
$file = 'counter.txt or whatever';
$handle = fopen ($file, 'r+'); // Let's open for read and write
$count = int (fread ($handle, filesize ($file)));
// We don't want to think it's a string and try appending
echo "Number of hits $count";
rewind ($handle); // Go back to the beginning
/*
* Note that we don't have problems with 9 being fewer characters than
* 10 because we are always incrementing, so we will always write at
* least as many characters as we read
**/
fwrite ($handle, ++$count); // Don't forget to increment the counter
fclose ($handle); // Done
?>


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