C++17 STL Cookbook

Check if multiple insertions into a set are successful

Let's write a helper that inserts an arbitrary number of variadic parameters into an std::set and returns if all the insertions are successful:

template <typename T, typename ... Ts>bool insert_all(T &set, Ts ... ts){    return (set.insert(ts).second && ...);}

So, how does this work? The insert function of std::set has the following signature:

std::pair<iterator, bool> insert(const value_type& value);

The documentation says that when we try to insert an item, the insert function will return an iterator and a bool variable in a pair. The bool value is true if the insertion is successful. If it is successful, the iterator points to the new element in the set. Otherwise, the iterator points ...