[TECK]

Another interesting way:
Simply comment your current code and add the new one, with "old code" tags.

Example:

PHP Code:

/* start old code
if ($vboptions['displayloggedin'])
{
    $datecut = TIMENOW - $vboptions['cookietimeout'];
    $numbervisible = 0;
    $numberregistered = 0;
    $numberguest = 0;
end old code */

if ($vboptions['displayloggedin'])
{
    $datecut = TIMENOW - $vboptions['cookietimeout'];
    $numbervisible = 0;
    $numberregistered = $numbervisible - $numberguest;
    $numberguest = 0; 


Then, you simply do a search for "old code" to compare.