How can create a function for unique file name - php

Question

I want to create a function which does rename the file and generate a unique name from its name, together with the user id. Below function is working properly but I'm not satisfied, kindly provide me the similar function.
if(is_array($file) and $file['name'] != '')
{
// getting unique file name
$file['name'] = getUniqueFilename($file);
$file_path = $file_root_path.$file['name'];
if(move_uploaded_file($file['tmp_name'], $file_path)){$filename = $file['name'];}
//
if($oldfile != ''){delete_file($file_root_path.$oldfile);}
return $filename;
} // if ends
else
{
return $oldfile;
} // else ends
function getUniqueFilename($file)
{
if(is_array($file) and $file['name'] != '')
{
// getting file extension
$fnarr = explode(".", $file['name']);
$file_extension = strtolower($fnarr[count($fnarr)-1]);
// getting unique file name
$file_name = substr(md5($file['name'].time()), 5, 15).".".$file_extension;
return $file_name;
} // ends for is_array check
else
{
return '';
} // else ends
} // ends

Answer 1

Use php uniqid() to generate unique ids http://php.net/manual/en/function.uniqid.php
function getUniqueFilename($file)
{
if(is_array($file) and $file['name'] != '')
{
// getting file extension
$file_extension = pathinfo($file['name'], PATHINFO_EXTENSION);
// getting unique file name
$file_name = uniqid().".".$file_extension;
while(file_exists('PATH_TO_WHERE_YOU_SAVE_FILE/'.$file_name)) {
$file_name = uniqid().".".$file_extension;
}
return $file_name;
} // ends for is_array check
else
{
return '';
} // else ends
} // ends

Answer 2

Take a hash of the file contents, e.g. with sha1_file. That guarantees a unique name for each unique file. If the same file gets uploaded a second time, it will generate the same hash, so you're not even storing duplicates of identical files.

Answer 3

Please use this code, that may help you
<?php
function tempdir($dir, $prefix='', $mode=0700)
{
if (substr($dir, -1) != '/') $dir .= '/';
do
{
$path = $dir.$prefix.mt_rand(0, 9999999);
} while (!mkdir($path, $mode));
return $path;
}
?>
Reference Link: http://www.php.net/manual/en/function.tempnam.php

Answer 4

You could create a filename with an [md5][1] hash salted with current [timestamp][2] and a random number.
Something like:
function getUniqueFilename($file)
{
do {
$name = md5(time().rand().$file['name']);
} while (file_exists($path.$name);
return $name;
}
Being path the folder where you want your file created