fgets

    (PHP 4, PHP 5, PHP 7, PHP 8)

    fgets — Gets line from file pointer

    Опис

    fgets(resource $stream, ?int $length = null): string|false

    Gets a line from file pointer.

    Параметри

    stream

    Вказівник на файл має бути дійсним та має вказувати на файл, успішно відкритий функцією fopen() або fsockopen() (та не закритий функцією fclose()).

    length

    Reading ends when length - 1 bytes have been read, or a newline (which is included in the return value), or an EOF (whichever comes first). If no length is specified, it will keep reading from the stream until it reaches the end of the line.

    Значення, що повертаються

    Returns a string of up to length - 1 bytes read from the file pointed to by stream. If there is no more data to read in the file pointer, then false is returned.

    If an error occurs, false is returned.

    Приклади

    Приклад #1 Reading a file line by line

    <?php

    $fp     = @fopen("/tmp/inputfile.txt", "r");

    if (    $fp) {
    while ((    $buffer = fgets($fp, 4096)) !== false) {
    echo     $buffer, PHP_EOL;
    }

    if (!    feof($fp)) {
    echo     "Error: unexpected fgets() fail\n";
    }

    fclose($fp);
    }

    ?>

    Примітки

    Зауваження: Якщо виникають проблеми з розпізнаванням закінчення рядків під час читання чи створення файлів на компʼютері Macintosh, може допомогти застосування директиви auto_detect_line_endings під час виконання.

    Зауваження:

    People used to the 'C' semantics of fgets() should note the difference in how EOF is returned.

    Прогляньте також

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    User Contributed Notes 31 notes

    up
    20
    Leigh Purdie
    9 years ago
    A better example, to illustrate the differences in speed for large files, between fgets and stream_get_line.

    This example simulates situations where you are reading potentially very long lines, of an uncertain length (but with a maximum buffer size), from an input source.

    As Dade pointed out, the previous example I provided was much to easy to pick apart, and did not adequately highlight the issue I was trying to address.

    Note that specifying a definitive end-character for fgets (ie: newline), generally decreases the speed difference reasonably significantly.

    #!/usr/bin/php
    <?php
    $plaintext    =file_get_contents('http://loripsum.net/api/60/verylong/plaintext'); # Should be around 90k characters
    $plaintext=str_replace("\n"," ",$plaintext); # Get rid of newlines

    $fp=fopen("/tmp/SourceFile.txt","w");
    for(    $i=0;$i<100000;$i++) {
    fputs($fp,substr($plaintext,0,rand(4096,65534)) . "\n");
    }
    fclose($fp);

    $fp=fopen("/tmp/SourceFile.txt","r");
    $start=microtime(true);
    while(    $line=fgets($fp,65535)) {
    1;
    }
    $end=microtime(true);
    fclose($fp);
    $delta1=($end - $start);

    $fp=fopen("/tmp/SourceFile.txt","r");
    $start=microtime(true);
    while(    $line=stream_get_line($fp,65535)) {
    1;
    }
    $end=microtime(true);
    fclose($fp);
    $delta2=($end - $start);

    $pdiff=$delta1/$delta2;
    print     "stream_get_line is " . ($pdiff>1?"faster":"slower") . " than fgets - pdiff is $pdiff\n";
    ?>

    $ ./testcase.php
    stream_get_line is faster than fgets - pdiff is 1.760398041785

    Note that, in a vast majority of situations in which php is employed, tiny differences in speed between system calls are of negligible importance.
    up
    3
    Anonymous
    4 years ago
    if you for some reason need to get lines from a string instead of a file pointer, try

    <?php
    function string_gets(string $source, int $offset = 0, string $delimiter = "\n"): ?string
    {
    $len = strlen($source);
    if (    $len < $offset) {
    // out of bounds.. maybe i should throw an exception
    return null;
    }
    if (    $len === $offset) {
    // end of string..
    return null;
    }
    $delimiter_pos = strpos($source, $delimiter, $offset);
    if (    $delimiter_pos === false) {
    // last line.
    return substr($source, $offset);
    }
    return     substr($source, $offset, ($delimiter_pos - $offset) + strlen($delimiter));
    }

    ?>

    (i had a ~16GB string in-memory i needed to process line-by-line, but i would get memory-allocation-crash (on a 32GB ram system) if i tried explode("\n",$str); , so came up with this.. interestingly, fgets() seems to be faster than doing it in-ram-in-php, though. php 7.3.7)
    up
    4
    David at Weintraub.name
    17 years ago
    There's an error in the documentation:

    The file pointer must be valid, and must point to a file successfully opened by fopen() or fsockopen() (and not yet closed by fclose()).

    You should also add "popen" and "pclose" to the documentation. I'm a new PHP developer and went to verify that I could use "fgets" on commands that I used with "popen".
    up
    2
    Peter Schlaile
    17 years ago
    fscanf($file, "%s\n") isn't really a good substitution for fgets(), since it will stop parsing at the first whitespace and not at the end of line!

    (See the fscanf page for details on this)
    up
    1
    tavernadelleidee[italy]
    18 years ago
    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
    up
    1
    afwxkat at gmail dot com
    15 years ago
    One thing I discovered with fgets, at least with PHP 5.1.6, is that you may have to use an IF statement to avoid your code running rampant (and possibly hanging the server). This can cause problems if you do not have root access on the server on which you are working.

    This is the code I have implemented ($F1 is an array):

    <?php
    if($fh = fopen("filename","r")){
    while (!    feof($fh)){
    $F1[] = fgets($fh,9999);
    }
    fclose($fh);
    }
    ?>

    I have noticed that without the IF statement, fgets seems to ignore when $fh is undefined (i.e., "filename" does not exist). If that happens, it will keep attempting to read from a nonexistent filehandle until the process can be administratively killed or the server hangs, whichever comes first.
    up
    0
    anacreo has gmail
    17 years ago
    I'm using this function to modify the header of a large postscript document on copy... Works extremely quickly so far...

    function write($filename) {
    $fh = fopen($this->sourceps,'r');
    $fw = fopen($filename,'w');

    while (!feof($fh)) {
    $buffer = fgets($fh);
    fwrite($fw,$buffer);
    if (!$setupfound && ereg("^%%BeginSetup",$buffer)) {
    $setupfound++;
    if (array_key_exists("$filename",$this->output)) {
    foreach ($this->output[$filename] as $function => $value) {
    fwrite($fw,$value);
    }
    }
    stream_copy_to_stream($fh,$fw);
    }
    }
    fclose($fw);
    fclose($fh);
    }
    up
    0
    angelo [at] mandato <dot> com
    20 years ago
    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);
    ?>
    up
    -1
    d at foo.com
    18 years ago
    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.
    up
    -1
    sam dot bryan at montal dot com
    18 years ago
    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;
    }
    ?>
    up
    -1
    Carlo
    6 years ago
    Error in the example number 1 of this page.

    change this line:
    $buffer = fgets($fd, 4096);
    into:
    $buffer = fgets($handle, 4096);
    up
    -3
    Leigh Purdie
    16 years ago
    For large files, consider using stream_get_line rather than fgets - it can make a significant difference.

    $ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=stream_get_line($fp,65535,"\n")) { 1; } fclose($fp);'

    real 0m1.482s
    user 0m1.616s
    sys 0m0.152s

    $ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=fgets($fp,65535)) { 1; } fclose($fp);'

    real 0m7.281s
    user 0m7.392s
    sys 0m0.136s
    up
    -1
    dandrews OVER AT 3dohio DOT com
    19 years ago
    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);
    }
    ?>
    up
    -2
    Anonymous
    18 years ago
    Macintosh line endings mentioned in docs refer to Mac OS Classic. You don't need this setting for interoperability with unixish OS X.
    up
    -2
    ecvej
    18 years ago
    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;
    }
    ?>
    up
    -3
    bfb1985 at yahoo dot es
    8 years ago
    I had loads of trouble while reading with fgets on a WAMP (Windows server). On local the file went unto a <pre> tag without a hitch, but when I moved the code to a LAMP production server, every \r\n created two fgets and I got free empty lines.

    I tried deleting with $string=str_replace("\r\n","\n",$string); but it had no effect whatsoever. The solution was to do an fread() and explode the contents by PHP_EOL and do a foreach($lines as $line) so every line did not get duplicated.

    Here is the example code:

    $file=fopen("test.txt,"r");
    $text=fread($file,filesize("test.txt"));
    $lines=explode(PHP_EOL,$text);
    foreach($lines as $line)
    {
    // Do something
    }
    up
    -3
    kpeters AT-AT monolithss DEE OH TEE com
    18 years ago
    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");
    }
    }
    up
    -3
    lzsiga at freemail.c3.hu
    14 years ago
    Some people try to call feof before fgets, and then ignoring the return value of fgets. This method leads to processing value FALSE when reaching the end of file.

    Bad example:
    <?php
    $f     = fopen ("fgetstest.php", "r");
    $ln= 0;
    while (!     feof ($f)) {
    $line= fgets ($f);
    ++    $ln;
    printf ("%2d: ", $ln);
    if (    $line===FALSE) print ("FALSE\n");
    else print (    $line);
    }
    fclose ($f);
    ?>

    Good example:
    <?php
    $f     = fopen ("fgetstest.php", "r");
    $ln= 0;
    while (    $line= fgets ($f)) {
    ++    $ln;
    printf ("%2d: ", $ln);
    if (    $line===FALSE) print ("FALSE\n");
    else print (    $line);
    }
    fclose ($f);
    ?>
    up
    -3
    Anonymous
    6 years ago
    <form>
    <input type='text' name='filepath' value='<?php echo ((isset($_GET["filepath"])) ? $_GET["filepath"] : "");?>'>
    <br>
    <select name='sel'>
    <option value='var1' <?php echo ((isset($_GET["sel"]) && $_GET["sel"] == "var1") ? "selected=true" : "");?>> For Year</option>
    <option value='var2' <?php echo ((isset($_GET["sel"]) && $_GET["sel"] == "var2") ? "selected=true" : "");?>>Name</option>
    <option value='var3' <?php echo ((isset($_GET["sel"]) && $_GET["sel"] == "var3") ? "selected=true" : "");?>>Name&Year</option>
    </select>
    <br>
    <input type='submit' value='Button'>

    </form>

    <?php

    if((!isset($_GET['filepath']) || !file_exists($_GET['filepath'])) || !isset($_GET['sel']))
    exit(    "");

    echo     "List<br>";
    $fullPath = "D:\\OSPanel\\domains\\" . $_GET["filepath"];
    $f = fopen($fullPath, "r");
    $arr;
    for(    $i = 0; $str = fgets($f); $i++){
    $tempArr0 = explode('-', $str);
    $arr[$i][0] = trim($tempArr0[0]);
    $arr[$i][1] = trim($tempArr0[1]);
    }

    if(    $_GET["sel"] == "var1"){
    sort($arr);
    echo     "<p>";
    for(    $i = 0; $i < count($arr); $i++)
    echo     "<i>{$arr[$i][0]}</i>; ";
    echo     "</p>";
    }
    else if(    $_GET["sel"] == "var2"){
    for(    $i = 0; $i < count($arr); $i++)
    echo     "<p><b>{$arr[$i][1]}</b></p>";
    }
    else if(    $_GET["sel"] == "var3"){
    for(    $i = 0; $i < count($arr); $i++)
    echo     "<p><b>{$arr[$i][1]}</b>: <i>{$arr[$i][0]}</i></p>";
    }

    ?>
    up
    -2
    lelkesa
    20 years ago
    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.
    up
    -2
    Anonymous
    20 years ago
    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));
    }

    }

    ?>
    up
    -5
    Dade Brandon
    11 years ago
    Regarding Leigh Purdie's comment (from 4 years ago) about stream_get_line being better for large files, I decided to test this in case it was optimized since then and I found out that Leigh's comment is just completely incorrect

    fgets actually has a small amount of better performance, but the test Leigh did was not set up to produce good results

    The suggested test was:

    $ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=stream_get_line($fp,65535,"\n")) { 1; } fclose($fp);'

    0m1.616s

    $ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=fgets($fp,65535)) { 1; } fclose($fp);'

    0m7.392s

    The reason this is invalid is because the buffer size of 65535 is completely unnecessary

    piping the output of "yes 'this is a test line'" in to PHP makes each line 19 characters plus the delimiter

    so while I don't know why stream_get_line performs better with an oversize buffer, if both buffer sizes are correct, or default, they have a negligable performance difference - although notably, stream_get_line is consistent - however if you're thinking of switching, make sure to be aware of the difference between the two functions, that stream_get_line does NOT append the delimiter, and fgets DOES append the delimiter

    Here are the results on one of my servers:

    Buffer size 65535
    stream_get_line: 0.340s
    fgets: 2.392s

    Buffer size of 1024
    stream_get_line: 0m0.348s
    fgets: 0.404s

    Buffer size of 8192 (the default for both)
    stream_get_line: 0.348s
    fgets: 0.552s

    Buffer size of 100:
    stream_get_line: 0.332s
    fgets: 0.368s
    up
    -3
    svayn at yahoo dot com
    18 years ago
    fgets is SLOW for scanning through large files. If you don't have PHP 5, use fscanf($file, "%s\n") instead.
    up
    -3
    Daniel Klein
    16 years ago
    The file pointer that fgets() uses can also be created with the proc_open() function and used with the stdout pipe created from the executed process.
    up
    -3
    timr
    20 years ago
    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.
    up
    -3
    dan at censornet dot com
    12 years ago
    WARNING! fgets() and I presume any read() call to a file handle, e.g.

    while(!feof(STDIN)) {
    $line = fgets(STDIN);

    ...do something useful with $line...
    }

    ...will result in a timeout after a default time of 60 seconds on my install. This behavior is non standard (not POSIX like) and seems to me to be a bug, or if not a major caveat which should be documented more clearly.

    After the timeout fgets() will return FALSE (=== FALSE), however, you can check to see if the stream (file handle) has really closed by checking feof($stream), e.g.

    while(!feof(STDIN)) {
    $line = fgets(STDIN);

    if($line === FALSE) {
    if(feof(STDIN)) {
    break;
    }
    continue;
    }

    ...do something useful with $line...
    }
    up
    -2
    alex at alex-at dot ru
    9 years ago
    For anyone who wants a proper non-blocking fgets for sockets, there is a tiny snippet that does just that (performance should be horrible compared to fgets though):

    <?php
    function read_line_nb($handle)
    {
    static     $buffer = '';
    static     $lastOffset = 0;

    $buffer .= fread($handle, 0x1000);
    if (    preg_match('#\\R#', $buffer, $m, PREG_OFFSET_CAPTURE, $lastOffset)) {
    $line = substr($buffer, 0, $m[0][1] + strlen($m[0][0]));
    $buffer = substr($buffer, $m[0][1] + strlen($m[0][0]));
    return     $line;
    }
    $lastOffset = strlen($buffer);
    return     false;
    }
    ?>
    up
    -4
    hackajar <matt> yahoo <trot> com
    18 years ago
    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);
    up
    -2
    zsjpxah
    5 years ago
    It's strange no one mentions "0" in this context.

    Since "0" is considered to be false, a line with a single "0" can be treated as EOF if using the while assign idiom.

    while ($line = fgets(STDIN, 2)) {
    }

    This may surprisingly break if a line starts with ")"
    up
    -4
    bogdan at insightmed dot eu
    8 years ago
    Even if this is not really related to PHP and its internals take care when using fgets for reading input from CLI on Linux systems as it may behave unexpected because of the limitations of arguments length on these systems. For example doing rtrim(fgets(STDIN), "\n") on a user input larger than 4095 characters will cut the the input string to 4095 characters. This shortcoming can be solved using "stty -icanon" before the script run, followed by a "stty icanon" after the script is run.
    up
    -4
    hgs at cs dot columbia dot edu
    13 years ago
    There seems to be an interaction between sockets and the auto_detect_line_endings setting that can cause rather peculiar behavior. Apparently, if the first line read from a socket is split across two TCP packets, the detector will look at the first TCP packet and determine that the system uses MacOS (\r) line endings, even though the LF is contained in the next packet. For example, this affected the PEAR Net_SMTP package, which would fail mysteriously for only some email servers.
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