can I have a map-like class with TWO key?

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I have a record like this:

C++

struct WORD
{
    int iID;
    char* pchWord;
    .
    .
    .
};

if I want to have my records in a map class and explore through them later, I can just have one variable as KEY to insert(), find(), and etc. But some times I like to explore through my records using their ID as well as their "pchWord" value; howwwwww

Posted 31-Oct-11 3:15am

Joseph Marzbani

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Nish Nishant · Accepted Answer · 2011-10-31T05:09:00

Richard has already suggested a very good way to do this. Here's a more C-ish alternative.

Replace the int iID with a void* iID. You can continue to assign int values to it without overflow (on 32 bit and 64 bit targets).

Now just use a std::multimap to store your data. It allows multiple keys to map to the same values.

Now here's the caveat : you have to manually make sure that there are no collisions between iID and pchWord. A simple way to accomplish this is to use char[0] arrays to get the iID values (making them unique addresses in the process memory space).

That said, I'd prefer Richard's suggestion myself. Consider my suggestion to be purely of academic interest (mostly for experimentation).

Richard MacCutchan · Accepted Answer · 2011-10-31T04:56:00

Solution 1

You could implement all functionality yourself, or perhaps have two maps, one of which uses the iID as a key to the pchWord or vice versa.

Posted 31-Oct-11 4:56am

Richard MacCutchan

Comments

CPallini 31-Oct-11 10:58am

I second the two maps idea.

Richard MacCutchan 31-Oct-11 11:01am

Thanks, it was the only thing I could think of!

Joseph Marzbani 31-Oct-11 11:06am

end up with a new class :-) OK guys, thnx