How to use binary_search on STL map

Question

im wondering if you can use the STL binary_search on STL map. I've tried but still cant get it to work

map<int,string> dataMap;

if(binary_search (dataMap.begin().first, dataMap.end().first, key))
    // do some stuff

Thanks in advance! :)

Answer 1

STL map is inherently a binary search tree - just use map::find . Using container member functions, where they are present, is preferable to algorithms.

Answer 2

Use std::map::lower_bound , std::map::find and std::map::upper_bound instead.

if(binary_search (dataMap.begin().first, dataMap.end().first, key))

binary_serach requires iterator. dataMap.begin().first and dataMap.end().first are not iterators. Another problem is that accessing dataMap.end().first is very likely to crash your application.