Re: [Boost-users] How to bind the first of a pair?

From: yinglcs2_at_[hidden]
Date: 2006-02-22 19:01:32

I am not sure how low_bound()  will work. 
My understanding is it only return the ** first **
instance.
but I am looking for ** all instances ** which fit the
condition (i.e. the first value of the key pair
matches the input parameter).

--- Peter Dimov <pdimov_at_[hidden]> wrote:

> Meryl Silverburgh wrote:
> > I have a map with key is a pair:
> > typedef map < pair<int, int>, string>
> pairMapString;
> >
> > pair<int, int> key(1,3);
> > map[key] = "one";
> >
> > How can I create a binary function using boost
> lamba which check the
> > first value of the pair of the key of the map?
> >
> > void add(pairMapString;& myMap, int x) {
> >
> > iterator& itr = find_if(myMap.begin(),
> myMap.end(),
> > bind(equal_to < int >(),
> >
>
bind(&BlockDataPairMap::value_type::first::value_type::first,
> _1 ) ,
> > x) );
> 
> myMap.lower_bound( make_pair( x, INT_MIN ) ) should
> give you what you need 
> in logarithmic time, if I'm not mistaken. 
> 
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>
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> 

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