Question

I have a list:

list<Unit *> UnitCollection;

containing Unit objects, which has an accessor like:

bool Unit::isUnit(string uCode)
{
    if(this->unitCode == uCode)
        return true;
    else
        return false;
}

How do I search my UnitCollection list by uCode and return the corresponding element (preferably and iterator).

In pseudo code it would look something like this:

for every item in my UnitCollection:
  if the unit.isUnit(someUnitIpass)
    do something
  else
    next unit

I have looked at the find() method, but i’m not sure you can pass a boolean method in instead of a searched item parameter if that makes sense.

Answer 1

You could have a look at find_if as jpalecek suggests, and then use distance to find the distance between the iterator returned from find_if and UnitCollection.begin(), and that distance should be the index of the element in the list.

And as for the predicate, you could write a function object like this:

struct predicate
{
    predicate( const std::string &uCode ) : uCode_(uCode) {}

    bool operator() ( Unit *u )
    {
        return u->isUnit( uCode_ )
    }
private:
    std::string uCode_;
};

And then use it like this:

predicate pred("uCode");
std::list<Unit*>::iterator i;
i = std::find_if( UnitCollection.begin(), UnitCollection.end(), pred );

Or at least I think that would be a way to do it.