How to get the relative directory no matter from where it's included in PHP?

Question

If it\'s Path_To_DocumentRoot/a/b/c.php,should always be /a/b.

I use this:

dirname($_SERVER[\"PHP_SELF\"])

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Answer 1

Here's a general purpose function to get the relative path between two paths.

/**
 * Return relative path between two sources
 * @param $from
 * @param $to
 * @param string $separator
 * @return string
 */
function relativePath($from, $to, $separator = DIRECTORY_SEPARATOR)
{
    $from   = str_replace(array('/', '\\'), $separator, $from);
    $to     = str_replace(array('/', '\\'), $separator, $to);

    $arFrom = explode($separator, rtrim($from, $separator));
    $arTo = explode($separator, rtrim($to, $separator));
    while(count($arFrom) && count($arTo) && ($arFrom[0] == $arTo[0]))
    {
        array_shift($arFrom);
        array_shift($arTo);
    }

    return str_pad("", count($arFrom) * 3, '..'.$separator).implode($separator, $arTo);
}

Examples

relativePath('c:\temp\foo\bar', 'c:\temp');              // Result: ../../
relativePath('c:\temp\foo\bar', 'c:\\');                 // Result: ../../../
relativePath('c:\temp\foo\bar', 'c:\temp\foo\bar\lala'); // Result: lala