Getting relative path from absolute path in PHP

Question

I noticed that there're some similar questions about this problem when I typed the title,but they seem not be in PHP.So what's the solution to it with a PHP function?

To be specified.

$a="/home/apache/a/a.php";
$b="/home/root/b/b.php";
$relpath = getRelativePath($a,$b);//needed function,should return '../../root/b/b.php'

Any good ideas?Thanks.

Answer 1

Relative path? This seems more like a travel path. You seem to want to know the path one travels to get from path A to path B. If that's the case, you can explode $a and $b on '/' then inversely loop through the $aParts, comparing them to $bParts of the same index until the "common denominator" directory is found (recording the number of loops along the way). Then create an empty string and add '../' to it $numLoops-1 times then add to that $b minus the common denominator directory.

Answer 2

Try this one:

function getRelativePath($from, $to)
{
    $from     = explode('/', $from);
    $to       = explode('/', $to);
    $relPath  = $to;

    foreach($from as $depth => $dir) {
        // find first non-matching dir
        if($dir === $to[$depth]) {
            // ignore this directory
            array_shift($relPath);
        } else {
            // get number of remaining dirs to $from
            $remaining = count($from) - $depth;
            if($remaining > 1) {
                // add traversals up to first matching dir
                $padLength = (count($relPath) + $remaining - 1) * -1;
                $relPath = array_pad($relPath, $padLength, '..');
                break;
            } else {
                $relPath[0] = './' . $relPath[0];
            }
        }
    }
    return implode('/', $relPath);
}

This will give

$a="/home/a.php";
$b="/home/root/b/b.php";
echo getRelativePath($a,$b), PHP_EOL;  // ./root/b/b.php

and

$a="/home/apache/a/a.php";
$b="/home/root/b/b.php";
echo getRelativePath($a,$b), PHP_EOL; // ../../root/b/b.php

and

$a="/home/root/a/a.php";
$b="/home/apache/htdocs/b/en/b.php";
echo getRelativePath($a,$b), PHP_EOL; // ../../apache/htdocs/b/en/b.php

and

$a="/home/apache/htdocs/b/en/b.php";
$b="/home/root/a/a.php";
echo getRelativePath($a,$b), PHP_EOL; // ../../../../root/a/a.php

Answer 3

Based on Gordon's function,my solution is as follows:

function getRelativePath($from, $to)
{
   $from = explode('/', $from);
   $to = explode('/', $to);
   foreach($from as $depth => $dir)
   {

        if(isset($to[$depth]))
        {
            if($dir === $to[$depth])
            {
               unset($to[$depth]);
               unset($from[$depth]);
            }
            else
            {
               break;
            }
        }
    }
    //$rawresult = implode('/', $to);
    for($i=0;$i<count($from)-1;$i++)
    {
        array_unshift($to,'..');
    }
    $result = implode('/', $to);
    return $result;
}

Answer 4

I would need modified code, with would have only the $from as parameter. After typing, please send a notification to: mcgiwer-at-yahoo-dot-com