Is it assured that the elelements in map are ordered

[baltasarq]

Hi !

This is a very specific question, regarding of course standard C++.

Say you have a map: map<int, string> m;, for example.
The main idea/use is that you can look for an int, and get the other
part of the pair.

But you can also run over it with a simple loop, using an interator.

iterator map<int, string>::iterator it = m.begin();
whie( it != end ) {
cout << it->second << endl;
++it;
}

The very specific question is:
Will these elements be printed in order, in STANDARD C++, i.e. in
every possible implementation of C++, or maybe -which is probably more
possible- the internal storing of the elemens in the map is compiler-
specific?

Regards,

Baltasar

 

[peter koch]

Hi !

This is a very specific question, regarding of course standard C++.

Say you have a map: map<int, string> m;, for example.
The main idea/use is that you can look for an int, and get the other
part of the pair.

But you can also run over it with a simple loop, using an interator.

iterator map<int, string>::iterator it = m.begin();
whie( it != end ) {
  cout << it->second << endl;
  ++it;

}

The very specific question is:
Will these elements be printed in order, in STANDARD C++, i.e. in
every possible implementation of C++, or maybe -which is probably more
possible- the internal storing of the elemens in the map is compiler-
specific?

It will printed in order.

/Peter

 

[Rolf Magnus]

Hi !

This is a very specific question, regarding of course standard C++.

Say you have a map: map<int, string> m;, for example.
The main idea/use is that you can look for an int, and get the other
part of the pair.

But you can also run over it with a simple loop, using an interator.

iterator map<int, string>::iterator it = m.begin();
whie( it != end ) {
cout << it->second << endl;
++it;
}

The very specific question is:
Will these elements be printed in order, in STANDARD C++, i.e. in
every possible implementation of C++, or maybe -which is probably more
possible- the internal storing of the elemens in the map is compiler-
specific?

The order is specific to the comparison function you use. If you don't
specify it explicitly, that's std::less, with which the map stores the
elements in ascending order.