PHP - Converting Strings And Arrays

Hello, I'm working on a script for my chat software that will convert an array into a string and then can easily later on be put back into an array, I've already done this but when I did it I didn't think of sub-arrays.

For example of an array:
Code: [Select]
$user_info = array(
 'username' => 'test',
 'other_info' => array(
  'var' => 'value',
  'var2' => 'value2'
 )
);

and that would change into something like this:
user_info:{username:test, other_info:{var:value,var2:value2}}

I do not care what the string looks like, above was just an example, any separators can be used. I just can't have it messed up by user input (a username with a character of a separator or something).

The code I have works for this:

Code: [Select]
$user_info = array('id' => 1, 'username' => 2);

and it outputs this as the string

id=1&username=2&

The code I use is:

Code: [Select]
function strtoarray($str)
{
$info = explode("&", $str);
if (is_array($info))
foreach ($info as $data)
{
$data = explode("=", $data);
if (is_array($data))
{
if (!empty($data[0]))
{
if ($array[$data[0]])
{
if (!is_array($array[$data[0]]))
{
$array[$data[0]] = array($array[$data[0]]);
}
$array[$data[0]][] = stripslashes(urldecode($data[1]));
}
else
{
$array[$data[0]] = stripslashes(urldecode($data[1]));
}
}
}
}
return $array;
}
function arraytostr($array)
{
foreach ($array as $key => $value)
{
$str .= $key . "=" . addslashes(urlencode($value)) . "&";
}
return $str;
}

I'm really not sure if regex is the way to go with this or what and that's really why I'm asking for help. I know I could do this with more explodes and what not but I feel as if there's probably a better way to do this and I'm just over complicating it.

Thank you in advance.