static initialization of stl map

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Lee Crabtree - 15 Sep 2005 20:47 GMT

I'm trying to fill a map (the STL associative array) with a set of values.
In the normal nomenclature, I could initialize an array something like this:

int array = {1, 2, 3, 4};

Is there anyway to initialize a map in a mildly similar way? I (naively,
apparently) assumed that I'd be able to do something along the lines of:

std::map<char, int> mapz0r = {('b', 1) ('a', 5)};

That is evidently RIGHT OUT. Does anyone know of a way to do something like
this?

Lee Crabtree

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Tamas Demjen - 15 Sep 2005 21:05 GMT

The closest thing that comes to that is this:
http://boost.org/libs/assign/doc/index.html

Take a look at list_of and map_list_of

Tom

> I'm trying to fill a map (the STL associative array) with a set of values.
> In the normal nomenclature, I could initialize an array something like this:
[quoted text clipped - 10 lines]
>
> Lee Crabtree

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Lee Crabtree - 16 Sep 2005 21:34 GMT

Alright, boost::assign seems to be what I'm looking for, but when I use
map_list_of, I get an error that I can't seem to find any info on:

error C2440: 'initializing' : cannot convert from
'boost::assign_detail::generic_list<T>' to 'std::map<_Kty,_Ty,_Pr,_Alloc>'
with
[
T=std::pair<boost::assign_detail::assign_decay<int>::type,boost::assign_detail::assign_decay<int>::type>
]
and
[
_Kty=int,
_Ty=int,
_Pr=std::less<int>,
_Alloc=std::allocator<std::pair<const int,int>>
]

The line that causes this error is:
map<int,int> blarg = map_list_of(1, 2);

This library definitely looks like what I'm looking for, but this error is
really weirding me out. Thanks for the suggestion, and if you know how to
fix this error, I would be forever in your debt.

Lee

> The closest thing that comes to that is this:
> http://boost.org/libs/assign/doc/index.html
[quoted text clipped - 18 lines]
>>
>> Lee Crabtree

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Carl Daniel [VC++ MVP] - 19 Sep 2005 21:44 GMT

> Alright, boost::assign seems to be what I'm looking for, but when I use
> map_list_of, I get an error that I can't seem to find any info on:
>
> error C2440: 'initializing' : cannot convert from
> 'boost::assign_detail::generic_list<T>' to 'std::map<_Kty,_Ty,_Pr,_Alloc>'

I'd suggest posting to the boost users mailing list. See www.boost.org for
subscription information.

-cd

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Hendrik Schober - 16 Sep 2005 13:46 GMT

> I'm trying to fill a map (the STL associative array) with a set of values.
> In the normal nomenclature, I could initialize an array something like this:
[quoted text clipped - 8 lines]
> That is evidently RIGHT OUT. Does anyone know of a way to do something like
> this?

Something along those lines:

// Beware! Uncompiled code...

typedef std::map<char,int> my_map_t;
typedef my_map_t::value_type my_map_entry_t;

const my_map_entry_t my_map_[] = { my_map_entry_t('b',1)
, my_map_entry_t('a',5) };

my_map_t my_map( my_map_, my_map_ + sizeof(my_map_)/sizeof(my_map_[0]) );

Not pretty, but doable.

> Lee Crabtree

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static initialization of stl map

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