Re: [Boost-users] [MultiIndex] Indexing integers

Sensei writes:

Dear all,

I am experimenting with MultiIndex, and I am happy with my custom classes.

Now I am wondering, can I index integers without a custom class?

For instance, say we have a 32 bit unsigned integer, how can I index these with respect to the MSB or LSB? [...]

You can define a function that does the MSB/LSB extraction and either pack it as a custom key extractor: http://www.boost.org/libs/multi_index/doc/ tutorial/key_extraction.html#user_defined_key_extractors or plug it into boost::multi_index::global_fun: http://www.boost.org/libs/multi_index/doc/ tutorial/key_extraction.html#global_fun The following example shows the latter approach for a multi_index_container of uint32_t's --you can easily adapt this to your particular scenario where the uint32_t's are members of a larger class. #include #include #include #include <cstdint> #include <iostream> using namespace boost::multi_index; inline uint16_t ls16half(uint32_t n) { return static_cast(n&0xFFFFul); } inline uint16_t ms16half(uint32_t n) { return static_cast(n>>16); } typedef multi_index_container< uint32_t, indexed_by< ordered_non_unique>, ordered_non_unique>

multi_t;

int main() { multi_t m={0x00030000ul,0x00020001ul,0x00010002ul,0x00000003ul}; std::cout<())std::cout<())std::cout<