fread

(PHP 4, PHP 5)

fread — Binary-safe file read

Description

string fread ( resource $handle , int $length )

fread() reads up to length bytes from the file pointer referenced by handle. Reading stops as soon as one of the following conditions is met:

length bytes have been read
EOF (end of file) is reached
a packet becomes available or the socket timeout occurs (for network streams)
if the stream is read buffered and it does not represent a plain file, at most one read of up to a number of bytes equal to the chunk size (usually 8192) is made; depending on the previously buffered data, the size of the returned data may be larger than the chunk size.

Parameters

handle: A file system pointer resource that is typically created using fopen().
length: Up to length number of bytes read.

Return Values

Returns the read string or FALSE on failure.

Examples

Example #1 A simple fread() example


<?php
// get contents of a file into a string
$filename = "/usr/local/something.txt";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
fclose($handle);
?>

Example #2 Binary fread() example

Warning

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


<?php
$filename = "c:\\files\\somepic.gif";
$handle = fopen($filename, "rb");
$contents = fread($handle, filesize($filename));
fclose($handle);
?>

Example #3 Remote fread() examples

Warning

When reading from anything that is not a regular local file, such as streams returned when reading remote files or from popen() and fsockopen(), reading will stop after a packet is available. This means that you should collect the data together in chunks as shown in the examples below.


<?php
// For PHP 5 and up
$handle = fopen("www.example.com/", "rb");
$contents = stream_get_contents($handle);
fclose($handle);
?>


<?php
$handle = fopen("www.example.com/", "rb");
$contents = '';
while (!feof($handle)) {
  $contents .= fread($handle, 8192);
}
fclose($handle);
?>

Notes

Note:
If you just want to get the contents of a file into a string, use file_get_contents() as it has much better performance than the code above.

Note:
Note that fread() reads from the current position of the file pointer. Use ftell() to find the current position of the pointer and rewind() to rewind the pointer position.

fwrite() - Binary-safe file write
fopen() - Opens file or URL
fsockopen() - Open Internet or Unix domain socket connection
popen() - Opens process file pointer
fgets() - Gets line from file pointer
fgetss() - Gets line from file pointer and strip HTML tags
fscanf() - Parses input from a file according to a format
file() - Reads entire file into an array
fpassthru() - Output all remaining data on a file pointer
ftell() - Returns the current position of the file read/write pointer
rewind() - Rewind the position of a file pointer

fscanf

fputs

[edit] Last updated: Fri, 15 Mar 2013

add a note User Contributed Notes fread - [50 notes]

down

shocker at shockingsoft dot com ¶

4 years ago


If you read from a socket connection or any other stream that may delay when responsing but you want to set a timeout you can use stream_set_timeout():



<?php

$f = fsockopen("127.0.0.1", 123);

if ($f)

 {

  fwrite($f, "hello");

  stream_set_timeout($f, 5); //5 seconds read timeout

  if (!fread($f, 5)) echo "Error while reading";

    else echo "Read ok";

  fclose($f);

 }

?>

down

ibis at connect dot ie ¶

8 years ago


If, like me, you're in the habit of using fopen("...") and fread for pulling fairly large remote files, you may find that the upgrade to PHP5 (5.0.2 on Win2000/IIS5) causes fread to top out at about 8035 bytes. PHP5 RC2 with identical php.ini settings did not exhibit this behaviour (I was using this for testing). Irritating for me because I was using simple_xml_load to load the file contents as XML, and the problem initially appeared to be that function.



Solution - swap over to file_get_contents or use the loop suggested on the documentation above (see Warning).

down

webmaster at wildpeaks dot com ¶

8 years ago


The following function retrieves a line in a file, regardless of its size, so you won't get an error if the file's size is beyond php's allowed memory limit (the string has to be below however), which is something i was needing for accessing a big log file generated by a webhost. Indexes start at 1 (so $line = 1 means the first line unlike arrays). If the file is small, it would be better to use "file()" however.





<?php


function strpos_count($haystack, $needle, $i = 0) {


    while (strpos($haystack,$needle) !== false) {$haystack = substr($haystack, (strpos($haystack,$needle) + 1)); $i++;}


    return $i;


}


function getLine($file,$line=1){


    $occurence = 0;


    $contents = '';


    $startPos = -1;


    if (!file_exists($file)) return '';


    $fp = @fopen($file, "rb");


    if (!$fp) return '';


    while (!@feof($fp)) {


        $str = @fread($fp, 1024);


        $number_of_occurences = strpos_count($str,"\n");


        if ($number_of_occurences == 0) {if ($start_pos != -1) {$contents .= $str;}}


        else {


            $lastPos = 0;


            for ($i = 0; $i < $number_of_occurences; $i++){


                $pos = strpos($str,"\n", $lastPos);


                $occurence++;


                if ($occurence == $line) {


                    $startPos = $pos;


                    if ($i == $number_of_occurences - 1) {$contents = substr($str, $startPos + 1);}


                } elseif ($occurence == $line + 1) {


                    if ($i == 0) {$contents .= substr($str, 0, $pos);} else {$contents = substr($str, $startPos, $pos - $startPos);}


                    $occurence = 0;


                    break;


                }


                $lastPos = $pos + 1;


            }


        }


    }


    @fclose($fp);


    return $contents;


}


?>

down

andrej dot frelih at gmail dot com ¶

1 year ago


Another sample function that supports from/to range requests:





<?php


function download_file($file_name) {





    if (!file_exists($file_name)) { die("<b>404 File not found!</b>"); }


    


    $file_extension = strtolower(substr(strrchr($file_name,"."),1));


    $file_size = filesize($file_name);


    $md5_sum = md5_file($file_name);


    


   //This will set the Content-Type to the appropriate setting for the file


    switch($file_extension) {


        case "exe": $ctype="application/octet-stream"; break;


        case "zip": $ctype="application/zip"; break;


        case "mp3": $ctype="audio/mpeg"; break;


        case "mpg":$ctype="video/mpeg"; break;


        case "avi": $ctype="video/x-msvideo"; break;





        //The following are for extensions that shouldn't be downloaded (sensitive stuff, like php files)


        case "php":


        case "htm":


        case "html":


        case "txt": die("<b>Cannot be used for ". $file_extension ." files!</b>"); break;





        default: $ctype="application/force-download";


    }


    


    if (isset($_SERVER['HTTP_RANGE'])) {


        $partial_content = true;


        $range = explode("-", $_SERVER['HTTP_RANGE']);


        $offset = intval($range[0]);


        $length = intval($range[1]) - $offset;


    }


    else {


        $partial_content = false;


        $offset = 0;


        $length = $file_size;


    }


    


    //read the data from the file


    $handle = fopen($file_name, 'r'); 


    $buffer = ''; 


    fseek($handle, $offset);


    $buffer = fread($handle, $length);


    $md5_sum = md5($buffer);


    if ($partial_content) $data_size = intval($range[1]) - intval($range[0]);


    else $data_size = $file_size;


    fclose($handle); 


 &nb

fread

Description

Parameters

Return Values

Examples

Notes

See Also