I had two vector’s with the first being the keys and the second being the values. It took a couple tries before I got the STL working for me!
The first thing was to check if the std::map constructors had something useful. It certainly seems like taking two sets of iterators would be a great way to initialize a map. No such luck.
So how about one of the std algorithms to copy the keys and values into the map? std::copy seemed likely but it only takes a single sequence. A little more digging and std::transform. The second version of std::transform takes two sequences, an output iterator, and a binary function to convert the two values from the two sequences into something that can be inserted into the output iterator. Perfect.
So how to turn the two values into a pair suitable for std::map? The std::make_pair is exactly what is needed. The hard part is getting the syntax so you can pass it as a function: make_pair<std::string,int> in this example.
So the code finally looks like:
include
include
include
include
include
include
void test()
{
std::map m;
std::vector keys;
std::vector values;
std::transform (keys.begin(), keys.end(),
values.begin(),
std::inserter (m, m.begin()),
std::make_pair<std::string,int>);
}
Tags: c#