The filesize() function in PHP is an inbuilt function which is used to return the size of a specified file. The filesize() function accepts the filename as a parameter and returns the size of a file in bytes on success and False on failure. The result of the filesize() function is cached and a function called clearstatcache() is used to clear the cache. Syntax:

filesize($filename)

Parameters: The filesize() function in PHP accepts only one parameter $filename. It specifies the filename of the file whose size you want to check. Return Value: It returns the size of a file in bytes on success and False on failure. Errors And Exception:

1. For files which are larger than 2GB some filesystem functions may return unexpected results since PHP's integer type is signed and many platforms use 32bit integers.
2. The buffer must be cleared if the filesize() function is used multiple times.
3. The filesize() function emits an E_WARNING in case of a failure.

Examples:

Input : echo filesize("gfg.txt");
Output : 256

Input : $myfile = 'gfg.txt';
        echo $myfile . ': ' . filesize($myfile) . ' bytes';
Output : gfg.txt : 256 bytes

Below programs illustrate the filesize() function. Program 1:

<?php

// displaying file size using
// filesize() function
echo filesize("gfg.txt");

?>

Output:

256

Program 2:

<?php

// displaying file size using
// filesize() function
$myfile = 'gfg.txt';

echo $myfile . ': ' . filesize($myfile) . ' bytes';

?>

Output:

gfg.txt : 256 bytes

Reference: http://php.net/manual/en/function.filesize.php