display string sub vector C++ - c++

Question

I am new in C++, I created a struct called Device with two fields
string MacAdress
vector<string> RSSI
Then, I created a vector of structure: vector<Device> Devices
I want to extract the vector<string> RSSI and display its contant.
Here is where I got stuck in my main.cpp:
cout << "display MAC and RSSI"<< endl;
Device CurrentDevice;
for(int j=0; j<Devices.size();j++)
{
CurrentDevice = Devices.at(j);
vector<string>::const_iterator begin = CurrentDevice.GetRSSIs().begin();
vector<string>::const_iterator last = CurrentDevice.GetRSSIs().begin() + CurrentDevice.GetRSSIs().size();
vector<string> intermed(begin+1, last);
cout << "Size: "<< intermed.size() << endl;
for (int i = 0 ; i < intermed.size(); i++)
{
cout << intermed[i] << endl;
cout << "device n°"<< j+1<<" " << "MAC "<< " "<< CurrentDevice.GetMacAdress()<< endl;
for(int k=0; k<intermed.size();k++)
{
cout << "device n°" << j;
cout << "\tRSSI " << k << " = " << intermed.at(k)<< endl;
}
}
return 0;
}
I end up with Size=0

Answer 1

here is some simplified code that does not use iterators but should still do the job:
#include <iostream>
#include <string>
#include <vector>
int main()
{
struct Device {
std::string MacAddress;
std::vector<std::string> RSSI;
};
std::vector<Device> Devices;
// add some stuff to first object
Device CurrentDevice1;
CurrentDevice1.MacAddress = "A-B-C";
CurrentDevice1.RSSI.push_back("rssi11");
CurrentDevice1.RSSI.push_back("rssi12");
CurrentDevice1.RSSI.push_back("rssi13");
Devices.push_back(CurrentDevice1);
// add some stuff to second object
Device CurrentDevice2;
CurrentDevice2.MacAddress = "D-E-F";
CurrentDevice2.RSSI.push_back("rssi21");
CurrentDevice2.RSSI.push_back("rssi22");
Devices.push_back(CurrentDevice2);
// see object MAC's
for (int i = 0; i < Devices.size(); i++){
std::cout << "device " << i+1 << " MAC: " << Devices[i].MacAddress << std::endl;
}
// see object RSSI's
for (int j = 0; j < Devices.size(); j++){
for (int k = 0; k < Devices[j].RSSI.size(); k++){
std::cout << "device " << j + 1 << " RSSI: " << k +1 << " : " << Devices[j].RSSI[k] << std::endl;
}
std::cout << "\n";
}
return 0;
}

Answer 2

I'm not sure about what do you want to obtain, but I suppose the problem is in the following lines
vector<string>::const_iterator last = CurrentDevice.GetRSSIs().begin() + CurrentDevice.GetRSSIs().size();
vector<string> intermed(begin+1, last);
Do you want to obtain a copy of CurrentDevice.GetRSSIs()?
In this case, you can use begin() and end()
vector<string> intermed(CurrentDevice().GetRSSIs().begin(),
CurrentDevice().GetRSSIs().end());
or, simpler, invoke the copy constructor,
vector<string> intermed(CurrentDevice().GetRSSIs());