Briefly describe the method of obtaining file size and creation time in PHP-PHP Tutorial-php.cn

Briefly describe the method of obtaining file size and creation time in PHP

墨辰丷

Release： 2023-03-31 19:26:02

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This article mainly introduces the method of obtaining file size and file creation time in PHP. It involves the usage skills of filesize and fileatime functions in PHP. It has certain reference value. Friends in need can refer to this article.

The example describes how PHP obtains the file size and file creation time. The specific analysis is as follows:

php can display various attributes of the file, including the last access time, last modification time, file size, etc. of the file.

<HTML>
<HEAD>
<TITLE>Returning information about a file</TITLE>
</HEAD>
<BODY>
<?php
print "The size of the file is ";
print filesize( "samplefile.doc" );
print "<br>";
$atime = fileatime( "samplefile.doc" );
print "This file accessed on ";
print date("l, M d, Y g:i a", $atime);
print "<br>";
$mtime = filemtime( "samplefile.doc" );
print "This file was modified on ";
print date("l, M d, Y g:i a", $mtime);
print "<br>";
$ctime = filectime( "samplefile.doc" );
print "This file was changed on ";
print date("l, M d, Y g:i a", $ctime);
?>
</BODY>
</HTML>

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filemtime (string filename)

Returns the time when the file was last modified, and returns FALSE if an error occurs. The time is returned as a Unix timestamp, usable with date().

filectime (string filename)

Returns the time when the last inode of the file was modified, or FALSE if an error occurs. The time is returned as a Unix timestamp.

fileatime (string filename)

Returns the time when the file was last accessed, or FALSE if an error occurs. The time is returned as a Unix timestamp.

//////////////////////////////

filectime: linux last modification time
filemtime: last modification time
fileatime: last access time

////////////////////////////// ////////////////////////////////////////////////////

filemtime
(PHP 3, PHP 4)

filemtime -- Get the file modification time
Description

int filemtime (string filename)

Return the time when the file was last modified, and return FALSE if an error occurs. The time is returned as a Unix timestamp, usable with date().
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.
This function returns the time when the data block in the file was last written, that is, the time when the content of the file was last modified.

Example 1. filemtime() Example

<?php
// outputs e.g. somefile.txt was last modified: December 29 2002 22:16:23.
$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
  echo "$filename was last modified: " . date ("F d Y H:i:s.", filemtime($filename));

}
?>

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filectime
(PHP 3, PHP 4)

filectime -- Get the inode modification time of the file
Description

int filectime (string filename)

Returns the time when the last inode of the file was modified, or FALSE if an error occurs. The time is returned as a Unix timestamp.
Note: In most Unix file systems, a file is considered modified when its inode data is changed. That is, when the file's permissions, owner, all groups, or other metadata in the inode are updated. See filemtime() (this is the function you want to use to create a "last updated" footer in a web page) and fileatime().
Note that some Unix instructions describe ctime as the time when the file was created, which is wrong. In most Unix file systems there is no creation time for Unix files.
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.

Example 1. fileatime() Example

<?php

// 输出类似：somefile.txt was last changed: December 29 2002 22:16:23.

$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
  echo "$filename was last changed: " . date ("F d Y H:i:s.", filectime($filename));
}
?>

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fileatime
(PHP 3, PHP 4)

fileatime -- Get the upper limit of the file Access time
Description

int fileatime (string filename)

Returns the time when the file was last accessed, or FALSE if an error occurs. The time is returned as a Unix timestamp.
Note: The atime of a file should be changed whenever a block of data in this file is read. Performance is affected when an application regularly accesses a large number of files or directories. Some Unix file systems can turn off atime updates when loading to improve the performance of such programs. The USENET newsgroup spool is a common example. This function is useless in this file system.
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.
Example 1. fileatime() Example

<?php
// 输出类似：somefile.txt was last accessed: December 29 2002 22:16:23.
$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
  echo "$filename was last accessed: " . date ("F d Y H:i:s.", fileatime($filename));
}
?>

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