@antrik at users dot sf dot net
> 15-Nov-2004 10:40
> When using basename() on a path to a directory
> ('/bar/foo/'), the last path component ('foo') is returned,
> instead of the empty string one would expect. (Both PHP
> 4.1.2 and 4.3.8 on GNU/Linux.) No idea whether this is
> considered a bug or a feature -- I found it extremely
> annoying. Had to work around using: <?php
> $file=substr($path, -1)=='/'?'':basename($path)
> ?> Watch out!
There is a reason behind this -- and it has nothing to do with being a feature. PHP was heavily modeled off of the POSIX model. Many of the same functions you see in PHP are also in C, C++, and Java. These languages are modeled on POSIX as well.
The directory '/bar/foo/', when passed into the function basename(), will output 'foo' because *everything*, including directories, in the POSIX model, is a _file_. Most unix platforms, and all Windows platforms are (some Linux distributions are not) fully compliant to the POSIX model.
For example, the device file that contains information about your harddisk, in Linux, is probably stored in the _file_ /dev/hda.
Another example is that when you want to list information about your CPU or Memory using the Linux kernel, you might read the _file_ /proc/cpu/info.
Directories are no exception. Directories are no more different than your regular text file -- other than the fact that they describe a _file_-list of all files under it, and where the OS can access them. This means that even directories treat other directories as files.
The reason why we are made to think that directories are not files is because the kernel (the OS) simply treats these culprits differently. Your OS is lying to you! When you try to open up c:\windows in Notepad, you simply get a runaround because the Windows operating system knows it is a directory and knows how to treat it -- and knowing this it will not let you open it up for editing. For if you did that, you would probably lose the data in that directory. If you are familiar with C programming, you will know that if you lose information about a pointer to an object, the object gets lost in memory. The same would happen if you modified a directory in the wrong way. This is why the operating system protects its directories with the upmost care. (Some do anyway, hehe)
So when doing any kind of programming in PHP, C/++, Java, Ada, Perl, Python, Ruby, FORTRAN, and yes, even RPG IV (for all of you AS/400 folks out there working on the IFS), you must treat directories as files well.
This is why 'foo' is returned. For more information on POSIX, see http://en.wikipedia.org/wiki/POSIX
I hope this helps. Cheers.