Delete all items from a c++ std::vector

Question

I\'m trying to delete everything from a std::vector by using the following code

vector.erase( vector.begin(), vector.end() );

Answer 1

class Class;
std::vector vec = some_data;

for (unsigned int i=vec.size(); i>0;) {
    --i;
    delete vec[i];
    vec.pop_back();
}
// Free memory, efficient for large sized vector
vec.shrink_to_fit();

Performance: theta(n)

If pure objects (not recommended for large data types, then just vec.clear();