Page 337 - Beginning PHP 5.3

Chapter 11: Working with Files and Directories
Time - Related Properties

Besides their contents, files have other properties that can provide useful information. The available
properties depend on the operating system in which the files are created and modified. On UNIX
platforms such as Linux, for example, properties include the time the file was last modified, the time it
was last accessed, and the user permissions that have been set on the file.

PHP provides three time - related file functions:
❑ fileatime() — Returns the time at which the file was last accessed as a UNIX timestamp.

A file is considered accessed if its contents are read

❑ filectime() — Returns the time at which the file was last changed as a UNIX timestamp.
A file is considered changed if it is created or written, or when its permissions have been
changed

❑ filemtime() — Returns the time at which the file was last modified as a UNIX timestamp.
The file is considered modified if it is created or has its contents changed
A UNIX timestamp is an integer value indicating the number of seconds between the UNIX epoch
(midnight on January 1, 1970) and the specified time and date.

The getdate() function is very useful when working with UNIX timestamps. It returns an associative
array containing the date information present in a timestamp. The array includes such values as the year,
the month, the day of the month, and so on. For example, you can set a variable such as $myDate to the
value returned by getdate() , and then access the month component with $myDate[ “ month “ .
]
Find out more about working with dates and times in Chapter 16.

Retrieving a Filename from a Path

It ’ s often very useful to be able to separate a filename from its directory path, and the basename()
function does exactly that, taking a complete file path and returning just the filename. For example, the
following code assigns index.html to $filename :

$filename = basename( “/home/james/docs/index.html” );
You can specify a directory path instead, in which case the rightmost directory name is returned. Here ’ s
an example that assigns the value docs to $dir :

$dir = basename( “/home/james/docs” );
Basically, basename() retrieves the last whole string after the rightmost slash.

If you don ’ t want the filename extension, or suffix, you can strip that off too by supplying the suffix as a
second argument to basename() . The following example assigns “ myfile ” to $filename :

$filename = basename( “/home/james/docs/myfile.doc”, “.doc” );

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