PHP Unconference Europe 2015

feof

(PHP 4, PHP 5)

feofTests for end-of-file on a file pointer

Descrierea

bool feof ( resource $handle )

Tests for end-of-file on a file pointer.

Parametri

handle

Indicatorul fișierului trebuie să fie valid și trebuie să indice la un fișier deschis cu succes cu ajutorul fopen() sau fsockopen() (și să nu fie închis cu fclose()).

Valorile întoarse

Returns TRUE if the file pointer is at EOF or an error occurs (including socket timeout); otherwise returns FALSE.

Note

Avertizare

If a connection opened by fsockopen() wasn't closed by the server, feof() will hang. To workaround this, see below example:

Example #1 Handling timeouts with feof()

<?php
function safe_feof($fp, &$start NULL) {
 
$start microtime(true);

 return 
feof($fp);
}

/* Assuming $fp is previously opened by fsockopen() */

$start NULL;
$timeout ini_get('default_socket_timeout');

while(!
safe_feof($fp$start) && (microtime(true) - $start) < $timeout)
{
 
/* Handle */
}
?>

Avertizare

If the passed file pointer is not valid you may get an infinite loop, because feof() fails to return TRUE.

Example #2 feof() example with an invalid file pointer

<?php
// if file can not be read or doesn't exist fopen function returns FALSE
$file = @fopen("no_such_file""r");

// FALSE from fopen will issue warning and result in infinite loop here
while (!feof($file)) {
}

fclose($file);
?>

add a note add a note

User Contributed Notes 14 notes

up
3
dewi at dewimorgan dot com
2 years ago
Return values in the documentation are incorrectly stated. It says:

Returns TRUE if the file pointer is at EOF or an error occurs (including socket timeout); otherwise returns FALSE.

Correct text would be more like:

Returns FALSE if no filehandle was passed;
returns NULL if no filehandle was passed;
returns TRUE if the file pointer is at EOF or an error occurs (including socket timeout);
otherwise returns FALSE.

As an example, running the following from the commandline:

php -r 'echo
    "Empty: ".var_export(feof(), true)."\n".
    "Null: ".var_export(feof(NULL), true)."\n".
    "Undefined: ".var_export(feof($undef), true)."\n"
;'

This will output:

PHP Warning:  Wrong parameter count for feof() in Command line code on line 1
PHP Warning:  feof(): supplied argument is not a valid stream resource in Command line code on line 1
PHP Warning:  feof(): supplied argument is not a valid stream resource in Command line code on line 1

Empty: NULL
Null: false
Undefined: false

This can, as other commenters have reported, result in infinite loops and massive PHP error logfiles, if the file handle returned by fopen() is invalid for any reason.
up
2
sudo dot adam dot carruthers at gmail dot com
4 years ago
When using feof() on a TCP stream, i found the following to work (after many hours of frustration and anger):

NOTE: I used ";" to denote the end of data transmission.  This can be modified to whatever the server's end of file or in this case, end of output character is.

<?php
        $cursor
= "";
       
$inData = "";

        while(
strcmp($cursor, ";") != 0) {
           
$cursor = fgetc($sock);
           
$inData.= $cursor;
        }
       
fclose($sock);
        echo(
$inData);
?>

Since strcmp() returns 0 when the two strings are equal, it will return non zero as long as the cursor is not ";".  Using the above method will add ";" to the string, but the fix for this is simple.

<?php
        $cursor
= "";
       
$inData = "";

        
$cursor = fgetc($sock);
        while(
strcmp($cursor, ";") != 0) {
           
$inData.= $cursor;
        }
       
fclose($sock);
        echo(
$inData);
?>

I hope this helps someone.
up
2
ironoxid at libero dot it
8 years ago
I really thought that the feof() was TRUE when the logical file pointer is a EOF.
but no !
we need to read and get an empty record before the eof() reports TRUE.

So

$fp = fopen('test.bin','rb');
while(!feof($fp)) {
  $c = fgetc($fp);
  // ... do something with $c
  echo ftell($fp), ",";
}
echo 'EOF!';

prints for two time the last byte position.
If our file length is 5 byte this code prints

0,1,2,3,4,5,5,EOF!

Because of this, you have to do another check to verify if fgetc really reads another byte (to prevent error on "do something with $c" ^_^).

To prevent errors you have to use this code

$fp = fopen('test.bin','rb');
while(!feof($fp)) {
  $c = fgetc($fp);
  if($c === false) break;
  // ... do something with $c
}

but this is the same of

$fp = fopen('test.bin','rb');
while(($c = fgetc($fp))!==false) {
  // ... do something with $c
}

Consequently feof() is simply useless.
Before write this note I want to submit this as a php bug but one php developer said that this does not imply a bug in PHP itself (http://bugs.php.net/bug.php?id=35136&edit=2).

If this is not a bug I think that this need at least to be noticed.

Sorry for my bad english.
Bye ;)
up
1
Jet
7 years ago
To avoid infinite loop with fgets() just use do..while statement.

<?php
if ($f = fopen('myfile.txt', 'r')) do {
   
$line = fgets($f);
   
// do any stuff here...
} while (!feof($f));
fclose($f);
up
1
cmr at forestfactory dot de
7 years ago
Here's solution 3:

<?
$fp
= fopen("myfile.txt", "r");
while ( (
$current_line = fgets($fp)) !== false ) {
 
// do stuff to the current line here
}
fclose($fp);
?>

AFAICS fgets() never returns an empty string, so we can also write:

<?
$fp
= fopen("myfile.txt", "r");
while (
$current_line = fgets($fp) ) {
 
// do stuff to the current line here
}
fclose($fp);
?>
up
1
Tom
8 years ago
feof() is, in fact, reliable.  However, you have to use it carefully in conjunction with fgets().  A common (but incorrect) approach is to try something like this:

<?
$fp
= fopen("myfile.txt", "r");
while (!
feof($fp)) {
 
$current_line = fgets($fp);
 
// do stuff to the current line here
}
fclose($fp);
?>

The problem when processing plain text files is that feof() will not return true after getting the last line of input.  You need to try to get input _and fail_ before feof() returns true.  You can think of the loop above working like this:

* (merrily looping, getting lines and processing them)
* fgets used to get 2nd to last line
* line is processed
* loop back up -- feof returns false, so do the steps inside the loop
* fgets used to get last line
* line is processed
* loop back up -- since the last call to fgets worked (you got the last line), feof still returns false, so you do the steps inside the loop again
* fgets used to try to get another line (but there's nothing there!)
* your code doesn't realize this, and tries to process this non-existent line (typically by doing the same actions again)
* now when your code loops back up, feof returns true, and your loop ends

There's two ways to solve this:

1. You can put an additional test for feof() inside the loop
2. You can move around your calls to fgets() so that the testing of feof() happens in a better location

Here's solution 1:

<?
$fp
= fopen("myfile.txt", "r");
while(!
feof($fp)) {
 
$current_line = fgets($fp);
  if (!
feof($fp)) {
   
// process current line
 
}
}
fclose($fp);
?>

And here's solution 2 (IMHO, more elegant):

<?
$fp
= fopen("myfile.txt", "r");
$current_line = fgets($fp);
while (!
feof($fp)) {
 
// process current line
 
$current_line = fgets($fp);
}
fclose($fp);
?>

FYI, the eof() function in C++ works the exact same way, so this isn't just some weird PHP thing...
up
1
Anonymous
9 years ago
if you're worried the file pointer is invalid, TEST IT before you go into your loop... that way it'll never be an infinite loop.
up
1
honzam+php at ipdgroup dot com
6 years ago
Johannes: Remember note from stream_get_meta_data page: For socket streams this member [eof] can be TRUE  even when unread_bytes  is non-zero. To determine if there is more data to be read, use feof() instead of reading this item.

Another thing: better not rely on the "including socket timeout" part of when feof returns true. Just found program looping two days in while(!feof($fd)) fread ... with 20 seconds timeout in PHP 4.3.10.
up
0
Alwar
1 year ago
Don't use feof to test if you have readed all data sent by the other end of the socket. As i know it would return true only when the other end closes the connection.
up
0
Johannes
10 years ago
I found feof() to be a slow function when using a non-blocking connection.

The function stream_get_meta_data() returns much quicker and has a return field 'eof'.
up
-1
jakicoll
4 years ago
Please note that feof() used with TCP-Connections, returns false as long as the connection is open.
It even returns false when there is no data available.

BTW: Using feof() with HTTP for a single request, you should always make sure that you set the HTTP-Header "Connection" to "close" and _not_ to "keep-alive".
up
-1
m a p o p a at g m a i l. c o m
8 years ago
you  can avoid the infinite loop and filling the error logs
by an simple if statement
Here is the example

    $handle = fopen("http://xml.weather.yahoo.com/forecastrss?p=AYXX0008&u=f", "r");
    $xml = "";
    if ($handle)
    {
       while (!feof($handle))
       {
           $xml .= fread($handle, 128);
       }
        fclose($handle);
    }
up
-1
Anonymous
8 years ago
if you use fseek function to pos the pointer exceed the size the file,feof still return true.so note that when you use feof as the condition of while loop.
up
-1
Anonymous
9 years ago
if you hit an feof() infinite loop, watch out for resultant humongous logs, they can cripple a site with hard disk usage limits or run up excess usage fees.
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