STL Priority Queue on custom class

Question

I\'m having a lot of trouble getting my priority queue to recognize which parameter it should sort by. I\'ve overloaded the less than operator in my custom class but it does

Answer 1

You need to make your parameter const, because as of now you're giving it a non-cost reference, which means you might modify the object you're comparing with. (Which you aren't, and probably shouldn't).

You're not being const-correct. Your operator< doesn't make modifications to the Node, so the function should be const:

bool operator<(const Node &aNode) const;

After that, if you have trouble calling the getTotalCost() function, it's likely that it is not const as well. Mark it as const if it's not already:

int getTotalCost(void) const;

Your code is now (more) const-correct.

On a side note, binary operators are usually implemented outside the class:

class Node
{
public:
    // ...

    int getTotalCost(void) const;

    // ...
};

bool operator<(const Node& lhs, const Node& rhs)
{
    return lhs.getTotalCost() < rhs.getTotalCost();
}