hash_map question

[Stefan Istrate]

On http://www.sgi.com/tech/stl/hash_map.html it says that hash_map is
only an extension of the SGI implementation, not a part of the C++
standard. But in g++ 4.1.3 I can manage it to work using the header
<ext/hash_map> and the namespace __gnu_cxx. So, it is present in more
implementations, not just SGI. Is this a thing I can trust in? Will I
always find hash_map on all new g++ versions? Should I care about
portability or it is safe to use it?

 

[Ian Collins]

On http://www.sgi.com/tech/stl/hash_map.html it says that hash_map is
only an extension of the SGI implementation, not a part of the C++
standard. But in g++ 4.1.3 I can manage it to work using the header
<ext/hash_map> and the namespace __gnu_cxx. So, it is present in more
implementations, not just SGI. Is this a thing I can trust in? Will I
always find hash_map on all new g++ versions? Should I care about
portability or it is safe to use it?

Not if you want maximum portability. hash_map will be in the next
revision of the standard.

 

[Jeff Schwab]

Not if you want maximum portability. hash_map will be in the next
revision of the standard.

s/hash_map/unordered_map

 

[James Kanze]

Onhttp://www.sgi.com/tech/stl/hash_map.htmlit says that hash_map is
only an extension of the SGI implementation, not a part of the C++
standard. But in g++ 4.1.3 I can manage it to work using the header
<ext/hash_map> and the namespace __gnu_cxx. So, it is present in more
implementations, not just SGI. Is this a thing I can trust in? Will I
always find hash_map on all new g++ versions? Should I care about
portability or it is safe to use it?

Yes and no. I think most implementations do support some
variant of hash_map, or hashmap, sometimes in std::, and
sometimes in a separate namespace. There are subtle differences
between the implementations, however, so for maximum
portability, you'd want to wrap it in your own class.