PHP: a good way to universalize paths across OSs (slash directions)

Question

My simple concern is being able to handle paths across OSs, mainly in the regard of back and forward slashes for directory separators.

I was using DIRECTORY_SEPARATOR, however:

1. It's long to write

2. Paths may come from different sources, not necessarily controlled by you

I'm currently using:

    function pth($path)
    {
        $runningOnWindows = (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN');
        $slash = $runningOnWindows ? '\\' : '/';
        $wrongSlash = $runningOnWindows ? '/' : '\\' ;
        return (str_replace($wrongSlash, $slash, $path));
    }

Just want to know that there is nothing existing in the language that I'm reinventing,

Is there already an inbuilt PHP functon to do this?

Solution 1

I'm aware of DIRECTORY_SEPARATOR,

However: 1. It's long to write

Laziness is never a reason for anything

$path = (DIRECTORY_SEPARATOR === '\\')
      ? str_replace('/', '\\', $subject)
      : str_replace('\\', '/', $subject);

or

$path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);

This will in one step replace "the right one" with itself, but that doesnt make any difference.

If you know for sure, that a path exists, you can use realpath()

$path = realpath($path);

However, that is not required at all, because every OS understands the forward slash / as a valid directory separator (even windows).

Solution 2

You are missing the DIRECTORY_SEPARATOR predefined constant.

Solution 3

If you're going to pass those paths to standard PHP functions, you actually don't need to fix paths, as far as I can tell. Basic functions like file_get_contents or fopen work perfectly fine with any kind of path you throw at them.

Comments

[Pekka]

Well, it's not enough for what he wants to do (Build a generic method to convert any path to the current OS's format). But it's a start

[Waihon Yew]

@Pekka: Sure. But he can lose the custom OS detection, which IMHO is the most unpleasant thing in that code.

[Charles]

Hell, you can even mix slashes on Windows. 'C:\Foo\Bar/baz/what.php' is totally a legal path in PHP.

[KingCrunch]

Hehe, yeah, there is really no reason to think about that. As far as I know there is exactly one exception, where it makes a difference on win php.net/domdocument.load Also the solution is mentioned there ;)

[shealtiel]

"you can even mix slashes on Windows". Here is one example when this didn't work on windows: exec("rd path\with/mixed/slashes") regarded the / as a key for the command

[KingCrunch]

I dont know every pitfall on windows, but this topic is about a solution in php and a command executed via exec() has not that much to do with php.

[Pacerier]

@KingCrunch, You quoted him on "Laziness is never a reason for anything", but he definitely stated "Paths may come from different sources, not necessarily controlled by you" as the reason.

[KingCrunch]

@Pacerier No, that was on "[DIRECTOR_SEPERATOR is] long to write". Sure, different sources can be a problem, but read the entire answer. The easiest solution remains to use / always, because it is accepted by every OS. (There is one exception; something XMLish ... )

[Jason]

Linux is happy to see a trailing / when accessing a directory, but I'm not sure Windows would like that at all.

[TonyG]

fx_slsh($path) ? Are vowels too expensive in this economy? fix_slash($path)