Question

I have a list with all the elements as struct of form

typedef struct person_node{
    string name;
    string country;
}person;

std::list<person> list;

The list is already sorted on person name.

How do I use the inbuilt binary_search() function in this?

I already know how to use this binary_search() on a list with only numbers as data, but I wonder how can I use it for such a list.

I am using this binary function as:

binary_search (list.begin(), list.end(), value, compare_function);

Only thing I don’t know is, “What should I enter in place of value, if I need to look for a specific name in the list?”

Also I want an iterator to point to that node, if found.

Answer 1

You enter a person containing the name you want to find.

Also note that binary_search is only rarely useful (it only tells you whether the item is present, not where it is in the collection. It is doubly useless on a std::list, because it requires random-access iterators to work at all well (which std::list doesn’t provide).

So, what you probably want is an std::vector<person> or std::deque<person>, which you’ll probably want to search with std::lower_bound or std::upper_bound. std::lower_bound and std::upper_bound will each return an iterator to the item they found, giving you access to that object.