Say I'm uploading a chunked file and I have to recompose it. I know the total chunks and data from every iteration.
I founded code like this:
for ($i = 1; $i <= $num_chunks; $i++) {
$file = fopen($target_file.$i, 'rb');
$buff = fread($file, 2097152);
fclose($file);
$final = fopen($target_file, 'ab');
$write = fwrite($final, $buff);
fclose($final);
unlink($target_file.$i);
}
Apparently, the 2097152 value, has no meaning, at least to me. I read the php docs but couldn't understand too much. Could anyone explain me how I should choose that secon param of fread? And how the thing works?
The second parameter is the amount of data to read, as your reading this in one chunk you have to be sure that it is enough to process any chunk. The value you've set is 2MB, which may be enough, but you could change the code so that it reads it in smaller chunks and loops till the input is fully read.
I've also changed it to open the output file once and just write the contents as you go along...
$final = fopen($target_file, 'wb'); // Open for write and start from beginning of file
for ($i = 1; $i <= $num_chunks; $i++) {
$file = fopen($target_file.$i, 'rb');
while($buff = fread($file, 4096)) {
fwrite($final, $buff);
}
fclose($file);
unlink($target_file.$i);
}
fclose($final);
Related
I'm trying to delete one line from CSV file by its line number, which I get as a parameter in URL.
I saw some discussions here, but it was mainly "delete a line by its id stored in first column" and so on. I tried to make it in the same way as others in these discussions, but it does not work. I only changed the condition.
if (isset($_GET['remove']))
{
$RowNo = $_GET['remove']; //getting row number
$row = 1;
if (($handle = fopen($FileName, "w+")) !== FALSE)
{
while (($data = fgetcsv($handle, 1000, ";")) !== FALSE)
{
//Here, I don't understand, why this condition does not work.
if ($row != $RowNo)
{
fputcsv($handle, $data, ';');
}
$row++;
}
fclose($handle);
}
}
I supposed, that it should work for me too, BCS just condition was changed. But it does not. It clears the whole file. Could you help me with it, please?
Thank you very much for any advice. Daniel.
You could load the file as an array of lines by using file().
Then remove the line and write the file back.
// read the file into an array
$fileAsArray = file($FileName);
// the line to delete is the line number minus 1, because arrays begin at zero
$lineToDelete = $_GET['remove'] - 1;
// check if the line to delete is greater than the length of the file
if ($lineToDelete > sizeof($fileAsArray)) {
throw new Exception("Given line number was not found in file.");
}
//remove the line
unset($fileAsArray[$lineToDelete]);
// open the file for reading
if (!is_writable($fileName) || !$fp = fopen($fileName, 'w+')) {
// print an error
throw new Exception("Cannot open file ($fileName)");
}
// if $fp is valid
if ($fp) {
// write the array to the file
foreach ($fileAsArray as $line) {
fwrite($fp, $line);
}
// close the file
fclose($fp);
}
If you have a unix system you could also use sed command:
exec("sed -e '{$lineToDelete}d' {$FileName}");
Remember cleaning command parameters if user input used:
https://www.php.net/manual/de/function.escapeshellcmd.php
Option if your CSV can fit to memory:
// Read CSV to memory array
$lines = file($fileName, FILE_SKIP_EMPTY_LINES | FILE_IGNORE_NEW_LINES);
// Remove element from array
unset($lines[$rowNo - 1]); // Validate that element exists!
// Rewrite your CSV file
$handle = fopen($fileName, "w+");
for ($i = 0; $i < count($lines); $i++) {
fputcsv($handle, $data, ';');
}
fclose($handle);
Option if your CSV can not fit to memory:
Use code from question, just write to separate file and later replace it with actual file:
$handle = fopen($FileName, "r");
// Read file wile not End-Of-File
while (!feof($fn)) {
if ($row != $RowNo) {
file_put_contents($FileName . '.tmp', fgets($fn), FILE_APPEND);
}
$row++;
}
fclose($handle);
// Remove old file and rename .tmp to previously removed file
unlink($FileName);
rename($FileName . '.tmp', $FileName);
I want to take one text file, split it in half, and put one half in one file, then the remaining half in the next. How would one accomplish this?
an example would be: split.php?n=file.txt
$file = $_GET['n'];
$i = 1;
$fp = fopen("./server/php/files/".$file,'a+');
$fs = filesize("./server/php/files/".$file);
$lengthhalf = $fs / 2;
while(! feof($fp)) {
$contents = fread($fp,$lengthhalf);
file_put_contents('./server/php/files/[2]'.$file,$contents);
$i++;
}
This does the work, without reading the whole file (or half of it) at once in memory:
function split_in_halves($file, $half1, $half2) {
$size = filesize($file);
$fd = fopen($file, 'rb');
stream_copy_to_stream($fd, fopen($half1, 'wb'), $size/2);
stream_copy_to_stream($fd, fopen($half2, 'wb'));
}
split_in_halves('foo', '[1]foo', '[2]foo');
php how to get web image size in kb?
getimagesize only get the width and height.
and filesize caused waring.
$imgsize=filesize("http://static.adzerk.net/Advertisers/2564.jpg");
echo $imgsize;
Warning: filesize() [function.filesize]: stat failed for http://static.adzerk.net/Advertisers/2564.jpg
Is there any other way to get a web image size in kb?
Short of doing a complete HTTP request, there is no easy way:
$img = get_headers("http://static.adzerk.net/Advertisers/2564.jpg", 1);
print $img["Content-Length"];
You can likely utilize cURL however to send a lighter HEAD request instead.
<?php
$file_size = filesize($_SERVER['DOCUMENT_ROOT']."/Advertisers/2564.jpg"); // Get file size in bytes
$file_size = $file_size / 1024; // Get file size in KB
echo $file_size; // Echo file size
?>
Not sure about using filesize() for remote files, but there are good snippets on php.net though about using cURL.
http://www.php.net/manual/en/function.filesize.php#92462
That sounds like a permissions issue because filesize() should work just fine.
Here is an example:
php > echo filesize("./9832712.jpg");
1433719
Make sure the permissions are set correctly on the image and that the path is also correct. You will need to apply some math to convert from bytes to KB but after doing that you should be in good shape!
Here is a good link regarding filesize()
You cannot use filesize() to retrieve remote file information. It must first be downloaded or determined by another method
Using Curl here is a good method:
Tutorial
You can use also this function
<?php
$filesize=file_get_size($dir.'/'.$ff);
$filesize=$filesize/1024;// to convert in KB
echo $filesize;
function file_get_size($file) {
//open file
$fh = fopen($file, "r");
//declare some variables
$size = "0";
$char = "";
//set file pointer to 0; I'm a little bit paranoid, you can remove this
fseek($fh, 0, SEEK_SET);
//set multiplicator to zero
$count = 0;
while (true) {
//jump 1 MB forward in file
fseek($fh, 1048576, SEEK_CUR);
//check if we actually left the file
if (($char = fgetc($fh)) !== false) {
//if not, go on
$count ++;
} else {
//else jump back where we were before leaving and exit loop
fseek($fh, -1048576, SEEK_CUR);
break;
}
}
//we could make $count jumps, so the file is at least $count * 1.000001 MB large
//1048577 because we jump 1 MB and fgetc goes 1 B forward too
$size = bcmul("1048577", $count);
//now count the last few bytes; they're always less than 1048576 so it's quite fast
$fine = 0;
while(false !== ($char = fgetc($fh))) {
$fine ++;
}
//and add them
$size = bcadd($size, $fine);
fclose($fh);
return $size;
}
?>
You can get the file size by using the get_headers() function. Use below code:
$image = get_headers($url, 1);
$bytes = $image["Content-Length"];
$mb = $bytes/(1024 * 1024);
echo number_format($mb,2) . " MB";
In PHP if you write to a file it will write end of that existing file.
How do we prepend a file to write in the beginning of that file?
I have tried rewind($handle) function but seems overwriting if current content is larger than existing.
Any Ideas?
$prepend = 'prepend me please';
$file = '/path/to/file';
$fileContents = file_get_contents($file);
file_put_contents($file, $prepend . $fileContents);
The file_get_contents solution is inefficient for large files. This solution may take longer, depending on the amount of data that needs to be prepended (more is actually better), but it won't eat up memory.
<?php
$cache_new = "Prepend this"; // this gets prepended
$file = "file.dat"; // the file to which $cache_new gets prepended
$handle = fopen($file, "r+");
$len = strlen($cache_new);
$final_len = filesize($file) + $len;
$cache_old = fread($handle, $len);
rewind($handle);
$i = 1;
while (ftell($handle) < $final_len) {
fwrite($handle, $cache_new);
$cache_new = $cache_old;
$cache_old = fread($handle, $len);
fseek($handle, $i * $len);
$i++;
}
?>
$filename = "log.txt";
$file_to_read = #fopen($filename, "r");
$old_text = #fread($file_to_read, 1024); // max 1024
#fclose(file_to_read);
$file_to_write = fopen($filename, "w");
fwrite($file_to_write, "new text".$old_text);
Another (rough) suggestion:
$tempFile = tempnam('/tmp/dir');
$fhandle = fopen($tempFile, 'w');
fwrite($fhandle, 'string to prepend');
$oldFhandle = fopen('/path/to/file', 'r');
while (($buffer = fread($oldFhandle, 10000)) !== false) {
fwrite($fhandle, $buffer);
}
fclose($fhandle);
fclose($oldFhandle);
rename($tempFile, '/path/to/file');
This has the drawback of using a temporary file, but is otherwise pretty efficient.
When using fopen() you can set the mode to set the pointer (ie. the begginng or end.
$afile = fopen("file.txt", "r+");
'r' Open for reading only; place
the file pointer at the beginning of
the file.
'r+' Open for reading and
writing; place the file pointer at the
beginning of the file.
$file = fopen('filepath.txt', 'r+') or die('Error');
$txt = "/n".$string;
fwrite($file, $txt);
fclose($file);
This will add a blank line in the text file, so next time you write to it you replace the blank line. with a blank line and your string.
This is the only and best trick.
I am using a variation of the familiar readfile_chunked in attempt of download for larger files:
function readfile_chunked($filename)
{
$chunk_size = 1*(1024*1024); // how many bytes per chunk
$buffer = '';
$handle = fopen($filename, 'rb');
if ($handle === false)
{
return false;
}
while (!feof($handle))
{
$buffer = fread($handle, $chunk_size);
print $buffer;
ob_flush();
flush();
sleep(1);
}
$status = fclose($handle);
return $status;
}
smaller files work fine, but this larger file is missing the last 2830 bytes.
i found out the issue to this. under the php.ini file, make sure you set implicit_flushing to On. i still have the explicit flush code after each line outputted however.