On which line?
EDIT:
Oh, you did not #include <string>
Type: Posts; User: laserlight
On which line?
EDIT:
Oh, you did not #include <string>
I recommend using back_inserter instead of anticipating the number of elements in the result, e.g.,
vector<string> result;
std::set_difference(vec1.begin(), vec1.end(),
...