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urgent:search value in map

Posted on 2011-09-11
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Last Modified: 2012-05-12
Hi there,

I have a map like this:
 map<int,int> months;
months[key]=value.
I know we can find the key using the find function. months[key] but is it possible find the value of the months ?

Is it possible to search for value in a map ?
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Question by:zizi21
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3 Comments
 
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Expert Comment

by:Infinity08
ID: 36521019
Sure. If you iterate over the entire map, and check every item in it.

But probably that's not what you want. Most likely, you are using the wrong data structure for your needs.
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Author Comment

by:zizi21
ID: 36521042
I need to search for key and at times, the value. Is there any data structure that allows  me to do that?

I searched and there was boost bimap but they stated that make sure that this is what you are really after as it is a bit slow due to the redundancy being kept.
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LVL 53

Accepted Solution

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Infinity08 earned 2000 total points
ID: 36521566
There is indeed a trade-off to be taken into account. If you need to be able to efficiently perform lookups on both key and value, then you'll pay for that elsewhere (eg. in memory footprint, insertion time, ...).

If you only rarely have to look up a value, and the map is relatively small, and you can live with a slower performance when looking up by value, then you can keep using a map, and simply iterate over the entire contents to find the value.
If any of those preconditions are not true though, you'll likely be better off placing the trade-off elsewhere by using a different data structure.
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