Question

I have a:

vector<unsigned> v; 

How can I use the numbers/values in the vector as a Key to search a

map <unsigned, unsigned>& mp 

the map is formed by

map.insert(pair<unsigned, unsigned>(v, sthelse))

from another data sets.

Answer 1

You can’t use a vector<unsigned> as a key to search a map<unsigned, unsigned>. As the first template parameter to map<> indicates, the type of the key is unsigned, not vector<unsigned>.

You can use the members of the vector as keys to search the map, like this:

for(i = 0; i < v.size(); ++i) {
  auto it = mp.find(v[i]);
  if(it != mp.end()) {
    std::cout << "Look, Martha, we caught one! " << it->second << "\n";  
}