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std::map with keys that have no ordering


By : Francisco
Date : July 31 2020, 05:00 PM
it helps some times Your objects have to respect strict total order. That means, most importantly, your < relation must be irreflexive and transitive. In your case, consider just using std::tuple, which already provides a functioning operator< with lexicographical ordering.
This would be "a" correct ordering, but most likely not at all what you would want:
code :
friend bool operator<(Object const& a, Object const& b) {
  return a.x < b.x; // probably not what you want, but legal
}
friend bool operator<(Object const& a, Object const& b) {
  return a.x <= b.x; // this will break map
}


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ordering array keys?


By : Rishabh
Date : March 29 2020, 07:55 AM
I wish did fix the issue. i want to create an array with 2 keys and i want them in following order: , I think there's no easier way than
code :
$array = array("higher" => null, "escalate" => null);

Ordering by several keys in MongoDB


By : Mike
Date : March 29 2020, 07:55 AM
around this issue The syntax you use only works if your JavaScript implementation preserves the order of keys in objects. Most do, most of the time, but it's up to you to be sure.
For the Nodejs official driver, there is an alternate form that works with an Array:
code :
db.collection.find().sort([[age, -1], [score, 1]]);

Custom ordering of keys in map


By : Nick
Date : March 29 2020, 07:55 AM
it fixes the issue I'm making an exercise where I'm traversing a word ("pepper") and I'm counting the times each character is repeated and I would like the output be: , I only tested the code below with MS VC++ 2010.
code :
void foo( const std::string &word )
{
    auto order = [&]( char x, char y )
    {
        return ( word.find( x ) < word.find( y ) );
    };

    std::map<char, int, decltype( order )> m( order );
    for ( char c : word ) ++m[c];

    for ( const auto &p : m ) std::cout << p.first << ": " << p.second << std::endl;
    std::cout << std::endl;
}

Object.keys() ordering standard?


By : user3312593
Date : March 29 2020, 07:55 AM
hop of those help? The spec for Object.keys() is largely a wrapper around the spec-internal operation EnumerableOwnPropertyNames. This, in turn, states

Why is map.put not maintaining the ordering of keys


By : Dimitri Masin
Date : March 29 2020, 07:55 AM
wish help you to fix your issue If you want the ordering of the keys to be maintained you should use a LinkedHashMap which, by default, iterates over the keys according to their insertion order.
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