regex find all the strings preceded by = and ending in &

Question

I need to find in a large body of text all the strings that are between = and & symbols. I don't want the result strings to contain = and &, only whats between them.

Answer 1

If your regex engine supports lookbehinds/lookaheads:

(?<==).*?(?=&)

Otherwise use this:

=(.*?)&

and catch capture group 1.

If your regex engine does not support non-greedy matching replace the .*? with [^&]*.

---

But as zzzzBov mentioned in a comment, if you're parsing GET URL prefixes there are usually better native methods for parsing GET arguments.

In PHP for example there would be:

<?php
$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz
parse_str($str, $output);
echo $output['first'];  // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz
?>

(As found on php.net.)

Edit: Appears you're using Javascript.

Javascript solution for parsing query string into object:

var queryString = {};
anchor.href.replace(
    new RegExp("([^?=&]+)(=([^&]*))?", "g"),
    function($0, $1, $2, $3) { queryString[$1] = $3; }
);

Source: http://stevenbenner.com/2010/03/javascript-regex-trick-parse-a-query-string-into-an-object/