C++ RegExp and placeholders

I'm on C++11 MSVC2013, I need to extract a number from a file name, for example:

string filename = "s 027.wav";

If I were writing code in Perl, Java or Basic, I would use a regular expression and something like this would do the trick in Perl5:

filename ~= /(\d+)/g; 

and I would have the number "027" in placeholder variable $1.

Can I do this in C++ as well? Or can you suggest a different method to extract the number 027 from that string? Also, I should convert the resulting numerical string into an integral scalar, I think atoi() is what I need, right?