C++ function object to return `p->first` and `p->second`

Question

Is there a builtin function object that returns p->first and p->second, so that I can happily write

transform(m.begin(),m.end         


        

Answer 1

If you can use C++0x you can either use real lambdas since G++ 4.5 or you can use the new tuple-library which is fully compatible with std::pairs. Then you could use std::get<0> for first and std::get<1> for second.

If you are bound to C++98 you can use std::tr1::tuple instead of std::pair, as in TR1 get doesn't work with std::pair.

Also you can use bind from TR1 (tr1/functional) like Elazar described it.