Pass multiple variables by reference to a foreach loop (PHP) - php

Question

Scenario/Problem Isolation: Lets suppose my program uses MULTIPLE variables. At the program beginning I want to manipulate MANY of the variables AT ONCE through a general function with LITTLE CODE, before then later in the process using only distinctive few variables in specific functions.
Question: How do I pass multiple variables by reference to a foreach loop? Or is there a better/alternative method for looping through multiple determined variables?
Post(s) related to topic, but didn't solve my issue:
PHP foreach loop on multiple objects?
Background (for those concerned): I have a command line program which uses getopts http://hash-bang.net/2008/12/missing-php-functions-getopts/ to get various arguments, thus I get about 20 variables. I want to run all variables, which contain filepath(s) (about 10) through the "general" function reduceHierarchyDots() at ONCE (instead of calling the function 10 times).
<?php
/// The "general" function:
function reduceHierarchyDots ($file) {
while (preg_match('|./\.{2}/|', $file)) { $file = preg_replace('|/([^/]+)/\.{2}/|', '/', $file, 1); }
$file = preg_replace('|(/(\./)+)|', '/', $file);
$file = preg_replace('|^(\./)+|', '', $file);
return $file;
}
function reduceHierarchyDotsRef (&$file) {
while (preg_match('|./\.{2}/|', $file)) { $file = preg_replace('|/([^/]+)/\.{2}/|', '/', $file, 1); }
$file = preg_replace('|(/(\./)+)|', '/', $file);
$file = preg_replace('|^(\./)+|', '', $file);
}
/// The "many" variables:
$x = "something";
$y = 123;
$y = array ("a", "B", 3);
$a = "/Users/jondoe/Desktop/source/0.txt";
$b = "/Users/jondoe/Desktop/source/../1.txt";
$c = "/Users/jondoe/Desktop/source/../../2.txt";
$arrOne = array (
"v1" => "/some/thing/../1.pdf",
"v2" => "/some/thing/../../2.pdf",
"v3" => "/some/thing/../../../3.pdf"
);
$arrTwo = array (
"./1.doc",
"/so.me/.thing/ends./././2.doc",
"./././3.doc"
);
/// At the beginning I want to run multiple determined variables through a "general" function:
/// Debugging: Variables BEFORE the manipulation:
echo("BEFORE:\n"); var_dump($b, $arrOne["v2"], $arrTwo[2]); echo("\n");
/// Method works, but is long! (1 line/statement per function call)
reduceHierarchyDotsRef($b);
reduceHierarchyDotsRef($arrOne["v2"]);
reduceHierarchyDotsRef($arrTwo[2]);
/// Hence, I'd like to pass all variables by reference at once to a foreach loop:
//// These cause: Parse error: syntax error, unexpected '&':
// foreach ( array($b, $arrOne["v2"], $arrTwo[2] ) as &$file) { $file = reduceHierarchyDots($file); }
// foreach (array(&$b, &$arrOne["v2"], &$arrTwo[2] ) as &$file) { $file = reduceHierarchyDotsRef($file); }
//// These have no effect on the intended variables:
// foreach (array(&$b, &$arrOne["v2"], &$arrTwo[2] ) as $file) { $file = reduceHierarchyDots($file); }
// foreach (array(&$b, &$arrOne["v2"], &$arrTwo[2] ) as $file) { $file = reduceHierarchyDotsRef($file); }
/// Debugging: Variables AFTER the manipulation:
echo("AFTER:\n"); var_dump($b, $arrOne["v2"], $arrTwo[2]);
/// After the "general" function ran over various variables, the more specific actions happen: ...
?>

Answer 1

You could try generating an array of the variable names, then using variable variables:
$x = '/bees/../ham';
$y = 'some/other/path';
$arr = array('x', 'y');
foreach($arr as $item) {
reduceHierarchyDotsRef($$item);
}
not sure if this works with passing by reference, but I see not reason for it not to work.

Answer 2

Pass by reference is defined in the function signature:
function func(&$passByRef);
That's why your code is throwing errors.
See: http://php.net/manual/en/language.references.pass.php