Sorting a vector of custom objects

Question

How does one go about sorting a vector containing custom (i.e. user defined) objects.
Probably, standard STL algorithm sort along with a predicate (a fu

Answer 1

You could use functor as third argument of std::sort, or you could define operator< in your class.

struct X {
    int x;
    bool operator<( const X& val ) const { 
        return x < val.x; 
    }
};

struct Xgreater
{
    bool operator()( const X& lx, const X& rx ) const {
        return lx.x < rx.x;
    }
};

int main () {
    std::vector my_vec;

    // use X::operator< by default
    std::sort( my_vec.begin(), my_vec.end() );

    // use functor
    std::sort( my_vec.begin(), my_vec.end(), Xgreater() );
}