Find specific element of multimap

[francois.chartrand]

Hi,

I would like to know if there is a way to locate a specific pair in a
multimap ?

Example:

std::multimap<int,int> myMap;
std::multimap<int,int>::iterator myMapIterator;

myMap.insert(std::make_pair(1,10));
myMap.insert(std::make_pair(1,11));
myMap.insert(std::make_pair(1,12));
myMap.insert(std::make_pair(2,10));
myMap.insert(std::make_pair(2,11));
myMap.insert(std::make_pair(2,12));

myMapIterator myIterator = myMap.find(std::make_pair(2,10));

 

[Pete Becker]

I would like to know if there is a way to locate a specific pair in a
multimap ?

Not in general. multimap is designed for looking up keys, not keys and
values. You might be better off with a multiset, and various comparison
functions that look at either what is currently the key value or at the
entire element.

 

[Mark P]

Hi,

I would like to know if there is a way to locate a specific pair in a
multimap ?

Example:

std::multimap<int,int> myMap;
std::multimap<int,int>::iterator myMapIterator;

myMap.insert(std::make_pair(1,10));
myMap.insert(std::make_pair(1,11));
myMap.insert(std::make_pair(1,12));
myMap.insert(std::make_pair(2,10));
myMap.insert(std::make_pair(2,11));
myMap.insert(std::make_pair(2,12));

myMapIterator myIterator = myMap.find(std::make_pair(2,10));

On top of what Pete said, you can use lower_bound and upper_bound with
the desired key and then iterate over the range [LB,UB) to see if any of
the values match. (Or just iterate up from LB and define your own
stopping condition, which may be more efficient.)