Re: [Boost-users] boost::multi_index

Subject: Re: [Boost-users] boost::multi_index
From: Igor R (boost.lists_at_[hidden])
Date: 2011-04-06 16:30:48

2011/4/6  <ppatel_at_[hidden]>:
> Hello,
>
>
>
> I have a question regarding creating composite key/specifying length for
> arrays while using multi_index container based on following structure.
>
>
>
> struct TestStruct {
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  char firstKey[50];
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  char secondKeyPart[3];
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  uint32_t thirdKeyPart;
>
>                 ……Some other information….
>
> };
>
>
>
> Do I really read to specify this lengths for character arrays? If yes, how
> do I do that while specifying key parts as below?
>
> typedef multi_index_container <
>
> TestStruct,
>
> Â  indexed_by<
>
> Â Â Â  //non-unique as some subscribers might have more than one number
>
> Â Â Â  hashed_unique<
>
> Â Â Â Â Â Â composite_key<
>
> Â Â Â Â Â Â Â  TestStruct,
>
> Â Â Â Â Â Â Â  member<TestStruct, char*, &TestStruct::firstKeyPart>,
>
> Â Â Â Â Â Â Â  member<TestStruct, char*, &TestStruct::secondKeyPart>,
>
> Â Â Â Â Â Â Â  member<TestStruct, uint32_t, &TestStruct::thirdKeyPart>,
>
> Â Â Â Â Â  >
>
> Â Â Â  >
>
> Â  >
>
>> TS;

The above keys will hash the pointer values, which is probably not
what you want.
If you change plain C arrays to std::string, it will work as you expect.