How can I find, increment and replace in php?

Question

I have strings in the form \\d+_\\d+ and I want to add 1 to the second number. Since my explanation is so very clear, let me give you a few examples:

Answer 1

Here's the solution for the PHP 5.3 (now when PHP supports lambdas)

$new = preg_replace_callback("/(\d+_)(\d+)", function($matches)
{
    return $matches[1] . (1 + $matches[2]);
}
, $new);