>PHP: fgets - Manual

DescripciÃ³n

string fgets ( resource gestor [, int longitud] )

Devuelve una cadena de hasta longitud - 1 bytes leÃdos desde el archivo apuntado por gestor. La lectura termina cuando se han leÃdo longitud - 1 bytes, se alcanza un salto de lÃnea (el cual se incluye en el valor devuelto), o en EOF (lo que ocurra primero). Si no se especifica una longitud, el valor predeterminado es de 1k, o 1024 bytes.

Si ocurre un error, devuelve FALSE.

Errores comunes:

Aquellos acostumbrados a la semÃ¡ntice de fgets() en 'C', debe notar la diferencia en el modo en que EOF es devuelto.

El puntero de fichero debe de ser valido y debe de apuntar a un fichero abierto con exito por fopen() o fsockopen().

A continuaciÃ³n se presenta un ejemplo simple:
Ejemplo 1. Lectura de un archivo lÃnea a lÃnea

<?php $gestor = @fopen("/tmp/archivo_entrada.txt", "r"); if ($gestor) { while (!feof($gestor)) { $bufer = fgets($gestor, 4096); echo $bufer; } fclose ($gestor); } ?>

Nota: El parÃ¡metro longitud se hizo opcional en PHP 4.2.0, si se omite, se asume 1024 como la longitud de lÃnea. A partir de PHP 4.3, al omitir longitud, la lectura de la secuencia continuarÃ¡ hasta que se alcance el final de la lÃnea. Si la mayorÃa de lÃneas en el archivo superan los 8KB, es mÃ¡s eficiente en tÃ©rminos de recursos espicificar la longitud mÃ¡xima de lÃnea en su script.

Nota: Esta funciÃ³n es segura con material binario desde PHP 4.3. Las versiones anteriores no contaban con Ã©sta caracterÃstica.

Nota: Si sufre problemas con PHP no reconociendo los finales de lÃnea cuando lee archivos creados en un Macintosh (o leyendo archivos sobre uno), puede probar activando la opciÃ³n de configuraciÃ³n auto_detect_line_endings.

Vea tambiÃ©n fgetss() fread(), fgetc(), stream_get_line(), fopen(), popen(), fsockopen(), y stream_set_timeout().

add a note User Contributed Notes
fgets

d at foo.com
13-Aug-2006 01:03


For sockets, If you dont want fgets, fgetc etc... to block if theres no data there. set socket_set_blocking(handle,false); and socket_set_blocking(handle,true); to set it back again.

svayn at yahoo dot com
14-Jul-2006 02:21


fgets is SLOW for scanning through large files. If you don't have PHP 5, use fscanf($file, "%s\n") instead.

sam dot bryan at montal dot com
23-May-2006 02:09


An easy way to authenticate Windows Domain users from scripts running on a non-Windows or non-Domain box - pass the submitted username and password to an IMAP service on a Windows machine.



<?php

$server = 'imapserver';

$user = 'user';

$pass = 'pass';



if (authIMAP($user, $pass, $server)) {

    echo "yay";

} else {

    echo "nay";

}



function authIMAP($user, $pass, $server) {

    $connection = fsockopen($server, 143, $errno, $errstr, 30);



    if(!$connection) return false;



    $output = fgets($connection, 128); // banner

    fputs($connection, "1 login $user $pass\r\n");

    $output = fgets($connection, 128);

    fputs($connection, "2 logout\r\n");

    fclose($connection);



    if (substr($output, 0, 4) == '1 OK') return true;



    return false;

}

?>

24-Mar-2006 09:36


Macintosh line endings mentioned in docs refer to Mac OS Classic. You don't need this setting for interoperability with unixish OS X.

tavernadelleidee[italy]
09-Mar-2006 03:44


I think that the quickest way of read a (long) file with the rows in  reverse order is



<?php

$myfile = 'myfile.txt';

$command = "tac $myfile > /tmp/myfilereversed.txt";

passthru($command);

$ic = 0;

$ic_max = 100;  // stops after this number of rows

$handle = fopen("/tmp/myfilereversed.txt", "r");

while (!feof($handle) && ++$ic<=$ic_max) {

   $buffer = fgets($handle, 4096);

   echo $buffer."<br>";

}

fclose($handle);

?>



It echos the rows while it is reading the file so it is good for long files like logs.



Borgonovo

ecvej
04-Jan-2006 01:20


I would have expected the same behaviour from these bits of code:-



<?php



/*This times out correctly*/

while (!feof($fp)) {

    echo fgets($fp);

}



/*This times out before eof*/

while ($line=fgets($fp)) {

    echo $line;

}



/*A reasonable fix is to set a long timeout*/

stream_set_timeout($fp, 180);

while ($line=fgets($fp)) {

    echo $line;

}

?>

hackajar <matt> yahoo <trot> com
05-Dec-2005 12:17


When working with VERY large files, php tends to fall over sideways and die.  



Here is a neat way to pull chunks out of a file very fast and won't stop in mid line, but rater at end of last known line.  It pulled a 30+ million line 900meg file through in ~ 24 seconds.



NOTE: 

$buf just hold current chunk of data to work with.  If you try "$buf .=" (note 'dot' in from of '=') to append $buff, script will come to grinding crawl around 100megs of data, so work with current data then move on!



//File to be opened

$file = "huge.file";

//Open file (DON'T USE a+ pointer will be wrong!)

$fp = fopen($file, 'r');

//Read 16meg chunks

$read = 16777216;

//\n Marker

$part = 0;



while(!feof($fp)) {

    $rbuf = fread($fp, $read);

    for($i=$read;$i > 0 || $n == chr(10);$i--) {

        $n=substr($rbuf, $i, 1);

        if($n == chr(10))break;

        //If we are at the end of the file, just grab the rest and stop loop

        elseif(feof($fp)) {

            $i = $read;

            $buf = substr($rbuf, 0, $i+1);

            break;

        }

    }

    //This is the buffer we want to do stuff with, maybe thow to a function?

    $buf = substr($rbuf, 0, $i+1);

    //Point marker back to last \n point

    $part = ftell($fp)-($read-($i+1));

    fseek($fp, $part);

}

fclose($fp);

kpeters AT-AT monolithss DEE OH TEE com
01-Dec-2005 05:51


It appears that fgets() will return FALSE on EOF (before feof has a chance to read it), so this code will throw an exception:



while (!feof($fh)) {

  $line = fgets($fh);

  if ($line === false) {

    throw new Exception("File read error");

  }

}

dandrews OVER AT 3dohio DOT com
07-Jan-2005 11:11


Saku's example may also be used like this:



<?php

 @ $pointer = fopen("$DOCUMENT_ROOT/foo.txt", "r"); // the @ suppresses errors so you have to test the pointer for existence

   if ($pointer) {

     while (!feof($pointer)) {

         $preTEXT = fgets($pointer, 999);

         // $TEXT .= $preTEXT;  this is better for a string

        $ATEXT[$I] = $preTEXT;  // maybe better as an array

        $I++;

     }

     fclose($pointer);

   }

?>

angelo [at] mandato <dot> com
19-Nov-2004 06:43


Sometimes the strings you want to read from a file are not separated by an end of line character.  the C style getline() function solves this.  Here is my version:

<?php

function getline( $fp, $delim )

{

    $result = "";

    while( !feof( $fp ) )

    {

        $tmp = fgetc( $fp );

        if( $tmp == $delim )

            return $result;

        $result .= $tmp;

    }

    return $result;

}



// Example:

$fp = fopen("/path/to/file.ext", 'r');

while( !feof($fp) )

{

    $str = getline($fp, '|');

    // Do something with $str

}

fclose($fp);

?>

lelkesa
04-Nov-2004 02:54


Note that - afaik - fgets reads a line until it reaches a line feed (\\n). Carriage returns (\\r) aren't processed as line endings.

However, nl2br insterts a <br /> tag before carriage returns as well.

This is useful (but not nice - I must admit) when you want to store a more lines in one.

<?php

function write_lines($text) {

  $file = fopen('data.txt', 'a');

  fwrite($file, str_replace("\n", ' ', $text)."\n");

  fclose($file);

}



function read_all() {

  $file = fopen('data.txt', 'r');

  while (!feof($file)) {

    $line = fgets($file);

    echo '<u>Section</u><p>nl2br'.($line).'</p>';

  }

  fclose($file);

}

?>



Try it.

05-Sep-2004 03:05


If you need to simulate an un-buffered fgets so that stdin doesnt hang there waiting for some input (i.e. it reads only if there is data available) use this :

<?php



    function fgets_u($pStdn) {



            $pArr = array($pStdn);



        if (false === ($num_changed_streams = stream_select($pArr, $write = NULL, $except = NULL, 0))) {

            print("\$ 001 Socket Error : UNABLE TO WATCH STDIN.\n");

            return FALSE;

        } elseif ($num_changed_streams > 0) {

                return trim(fgets($pStdn, 1024));

        }

            

    }



?>

rstefanowski at wi dot ps dot pl
12-Aug-2004 09:03


Take note that fgets() reads 'whole lines'. This means that if a file pointer is in the middle of the line (eg. after fscanf()), fgets() will read the following line, not the remaining part of the currnet line. You could expect it would read until the end of the current line, but it doesn't. It skips to the next full line.

timr
16-Jun-2004 07:13


If you need to read an entire file into a string, use file_get_contents().  fgets() is most useful when you need to process the lines of a file separately.

Saku
04-Jun-2004 05:47


As a beginner I would have liked to see "how to read a file into a string for use later and not only how to directly echo the fgets() result. This is what I derived:

<?php

 @ $pointer = fopen("$DOCUMENT_ROOT/foo.txt", "r"); // the @ suppresses errors so you have to test the pointer for existence

   if ($pointer) {

      while (!feof($pointer)) {

         $preTEXT = fgets($pointer, 999);

         $TEXT = $TEXT . $preTEXT;

      }

      fclose($pointer);

   }

?>

flame
21-May-2004 08:44


fread is binary safe, if you are stuck with a pre 4.3 version of PHP.

Pete
22-Feb-2004 04:35


If you have troubles reading binary data with versions <= 4.3.2 then upgrade to 4.3.3

The binary safe implementation seems to have had bugs which were fixed in 4.3.3

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MANUAL DE PHP

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fgets

DescripciÃ³n