using STL to find all elements in a vector

Question

I have a collection of elements that I need to operate over, calling member functions on the collection:

std::vector v;
... // vector is popula         


        

Answer 1

std::vector v, matches;
std::vector::iterator i = v.begin();
MyPred my_pred;
while(true) {
    i = std::find_if(i, v.end(), my_pred);
    if (i == v.end())
        break;
    matches.push_back(*i);
}

For the record, while I have seen an implementation where calling end() on a list was O(n), I haven't seen any STL implementations where calling end() on a vector was anything other than O(1) -- mainly because vectors are guaranteed to have random-access iterators.

Even so, if you are worried about an inefficient end(), you can use this code:

std::vector v, matches;
std::vector::iterator i = v.begin(), end = v.end();
MyPred my_pred;
while(true) {
    i = std::find_if(i, v.end(), my_pred);
    if (i == end)
        break;
    matches.push_back(*i);
}