Question

I have a vector v of objects A in a Class B where each object has a member: int level. I want to find the maximum value of the level of all the objects in the vector v. To this end I use the function:

int B::findMaxLevel()
{
vector<int> levels;
vector<A*>::iterator it;

for(it=v.begin();it!=v.end();++it)
{
    if(find(levels.begin(), levels.end(), (*it)->getLevel())!=levels.end())
        levels.push_back((*it)->getLevel());
}

return *max_element(levels.begin(), levels.end());

}

However I get the error: Assertion Failed, vector iterator not deferencable.
Should I define an int iterator additionally? Is there a better way to implement the function I want?

Answer 1

I guess your problem is with the last line. an empty vector will result in this error at that line.

Actually you’re not filling levels at all. It should be ==levels.end() instead of !=levels.end()

Also, take a look at the example code in here, and try to use a user specified comparison function object instead of multiple copies.

    template <class ForwardIterator, class Compare>
    ForwardIterator max_element ( ForwardIterator first, ForwardIterator last, Compare comp );