std::map find_if condition style confusion

Question

I\'d like to use std::find_if to search for the first element in my map that has a certain value in a specific element of its value structure. I\'m a little confus

Answer 1

If you want to search also in values then may be better to use Boost Bimap in order not to be slow?

Answer 2

This doesn't have anything to do with std::bind1st or std::bind2nd. First of all, you have to keep in mind that the elements of a map are key-value pairs, in your case std::pair<int,ValueType>. Then you just need a predicate that compares the x member of the second member of yuch a pair against a specific value:

struct XEquals : std::unary_function<std::pair<int,ValueType>,bool>
{
    XEquals(int _x)
        : x(_x) {}
    bool operator()(const std::pair<int,ValueType> &v) const
        { return p.second.x == x; }
    int x;
};