Question

I have a map and I want the first column i.e (*it).first to be pushed back into a vector then (*it)->second to be pushed back into another vector

Is this the best way to do it?

std::vector<std::string>test;
for ( it=mymap.begin() ; it != mymap.end(); it++ )
{
    test.push_back((*it).first);
}

My other question is if i have a loop i.e
how would I insert all the integers i into (*it).first?

for(int i = 0; i < 10; i++)
{
    // 1 - 10 will go in (*it).first
}

I want to have some integers in (*it).first and have associated values in (*it).second;

Answer 1

Your first question, “how can I push the first column of my map into one vector and the 2nd column into another” is solved thus:

std::map<std::string, std::string> mymap;
std::vector<std::string> keys;
std::vector<std::string> values;
for ( std::map<std::string,std::string>::iterator it=mymap.begin() ; it != mymap.end(); ++it )
{
  keys.push_back(it->first);
  values.push_back(it->second);
}

Your second question, “how would insert all the integers i into (*it).first ?” is solved thus:

std::map<int, int> mymap2;
for(int i = 0; i < 10; i++)
{
  // Insert default value into map
  // This sets '(*it).first' to 'i' and
  // '(*it).second' to a default value (in
  // this case, 0).
  mymap2[i];
}

or

std::map<int, int> mymap3;
for(int i = 0; i < 10; i++)
{
  // Insert specified value into map
  // this sets '(*it).first' to 'i', and
  // '(*it).second' to the value returned from the function.
  maymap3[i] = ChooseSpecificValue(i);
}