Sorting Multi Levels

[asavage]

Are there any references for the algorithm to sort on more that 1 level.

I have a file with Date Sector Store

and I want to sort it Date and within Date by Sector and within Sector by Store

[jsmith]

It's all in the element "compare" function. The compare function is what enforces the ordering you want, not the sort.

[ne555]

Use a stable sorting algorithm, first by store, then by sector and last by date.
Or provide a compare function that take into account those three parameters, with its priority.

[asavage]

Not sure what you mean but I used this for a 1 level sort

	bool Store::operator< (Store rhs)
	{
		return (date < rhs.date);

	}

[jsmith]

Consider:

struct person_t {
    std::string lastName;
    std::string firstName;
};

bool operator<( const person_t& lhs, const person_t& rhs )
{
    if( lhs.lastName < rhs.lastName ) return true;
    if( rhs.lastName < lhs.lastName ) return false;
    return lhs.firstName < rhs.firstName;
}

[asavage]

Thanks!

[asavage]

I am assuming that I can have multiple overloaded operator<

So I can have different sorts based on the prototype.

[ne555]

bool Class::operator<(const Class &) const; Different prototypes?
You can have several compare functions (functions, static methods, function objects) and choose the one that you want.

[asavage]

Got it. Thanks!