A map[a,b,c] how to use ?

[tonnot]

I'd want to have a 3d map.
map[int index, string key, string info_value]

I know that 0 = "key1" , 1 = "key2" etc .
But, How can I access to the 'info_value' using the key ?

Can be the easy solution have two maps ?
map1[int index, string key]
map2[string key, string info_value]
So, it would be very easy :
map2[map1[7]] gives me the 'info_vale'.

But the question is , can I do it with a 3d map ?
Thanks.

[hamsterman]

I don't understand what you're trying to achieve. Is it a map that could have a string or an int as a key? If so, see http://www.boost.org/doc/libs/1_41_0/libs/multi_index/doc/index.html

[tonnot]

No.
I have a enum var, so its values are 0,1,2,3 .....
Also I have a map that store the string values of this enum
map[0]="enum_0" and so...

I have a function set_property (My_enum property). Write code for call this function is very easy and understandable. My IDE gives me autocompletion for it (It shows me My_enum elements when I write the code).

Now I have a map that links int values to string values(property from enum) . But, I have to store a value for the property 0,1,2, etc.
So , I could to use another map, or a vector, but I'd want to use a 3d map :
map [int key1, string key2, string value]
I dont want a multimap. Simply I'd want to do a search using the second element of the map. (I'd want a direct method, if not, I prefer to use two maps linked between them )
Thanks
Is it possible ?

Thanks

[hamsterman]

I still don't understand. Try writing code showing how you want to use a 3d map. Maybe that would clarify things.

If you want tu use a string (key2) index and get int and another string, you could use map< string, pair< int, string > > where pair could be replaced with a struct of your own.
If you want to use both a string (key2) and an int (key1) indices (naming them both 'key' implies that you do), multi index map is what you need.

[tonnot]

I'd want to do searchs on my map using two keys
So mymap[int key1, string key2, value].
But I think I cannot write mymap[]["peter"] (or something like this) isn't it ?
Thanks

[Zhuge]

You mean a nested map, like map<int, map<string, value_type> >? Something like that is perfectly legal.

[ashishkumar]

for a given [a,b,c] if [b,c] are unique pairs, i.e. for each b there will be a unique c, then you can also use a std::pair for b&c and then create a map[a , std::pair<b,c>], the data structure will depend on the nature of a,b &c. You can also wrap b & c in a struct/class and create a map[a, myClass(b,c)] . Nested map might be helpful if for one a, you may have many [b,c] pairs existing. ( same as multi-map).

[Galik]

If I understand you correctly then key1 and key2 have a one to one mapping. So it seems to me you want to access your value from either the int key or its corresponding std::string key. Is that right?

If so then I think you are going to need two separate maps. One to map the two keys and another to store the values against one of the keys:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

#include <map> #include <iostream> int main() { std::map<int, std::string> keymap; keymap[0] = "enum_0"; keymap[1] = "enum_1"; keymap[2] = "enum_2"; std::map<std::string, std::string> m; // insert m["enum_0"] = "value 0"; // access by std::string m[keymap[1]] = "value 1"; // access by int m["enum_2"] = "value 2"; // access by std::string // retrieve std::cout << m[keymap[0]] << '\n'; // access by int std::cout << m["enum_1"] << '\n'; // access by std::string std::cout << m[keymap[2]] << '\n'; // access by int }

value 0 value 1 value 2

Is that what you were getting at?

[tonnot]

Thanks Galik.
This is what I said at the beginning, I need two maps.

Thank you.