Question

Im trying to write a search function to get an element in std::list by suing std:find. But im stuck in the third parameter in the find argorithm, regard to this guy How to search for an element in an stl list? I did overload the operator == pretty much but it seems still not working with the std::find.

This is my code:

class Node
{
    string word;
    int count;

    public:
        Node(string _word) :word(_word), count(0) {}
        ~Node() {}

        const string& getWord() const{
            return word;
        }
        bool operator == (const Node& other) const {
            return (this->word.compare(other.word) == 0);
        }
};
const Node &getNode(const list<Node> &nodes, const string &word){
    list<Node>::iterator itr;
    itr = find(nodes.begin(), nodes.end(), new Node(word)); <-- no viable overload '='
    return *itr;
}

I’m going very crazy with that issue now, please suggest me some hints. Thanks

Answer 1

To get the code working just remove the new from the sort
call. However, this is not going to make your code any better.

You don’t check if the element was actually found and just dereference
the iterator. If the element wasn’t found, this is undefined behavior.

Now, how to fix this.

1. Don’t provide this function. If the user of Node has a list, she should be perfectly capable of calling std::sort himself.
2. You don’t want to write the boiler-plate of wrapping and you don’t need to. Your class is convertible from std::string due to the single argument constructor taking a string (this should take a string by reference, though). So you can just write std::find(begin(nodes), end(nodes), "foobar");.
3. You can also mark the constructor explicit (the converting behavior is not wanted most of the time) and then just add two free operator==(const Node&, const std::string&) and operator==(const std::string&, const Node&).

In any case. Remove using namespace std; from your headers.