Question

I have a std::map object as follows

typedef std::map<int,int> RoutingTable;
RoutingTable rtable;

and then I’ve initialized it in a function

 for (int i=0; i<getNumNodes(); i++)
 {
   int gateIndex = parentModuleGate->getIndex();
    int address = topo->getNode(i)->getModule()->par("address");
    rtable[address] = gateIndex; 
  }

Now I want to change the values in the rtable in another function. how can I achieve this?

Answer 1

Pass the rtable by reference:

void some_func(std::map<int, int>& a_rtable)
{
    // Either iterate over each entry in the map and
    // perform some modification to its values.
    for (std::map<int, int>::iterator i = a_rtable.begin();
         i != a_rtable.end();
         i++)
    {
        i->second = ...;
    }

    // Or just directly access the necessary values for
    // modification.
    a_rtable[0] = ...; // Note this would add entry for '0' if one
                       // did not exist so you could use
                       // std::map::find() (or similar) to avoid new
                       // entry creation.

    std::map<int, int>::iterator i = a_rtable.find(5);
    if (i != a_rtable.end())
    {
        i->second = ...;
    }
}