Create and return a vector by reference

Question

I am new to C++ and I really cannot understand what is wrong in the following.

I got a segmentation fault when I try to access the vector from the main function (I can see the Vector received message) while I would expect that the variable asd in the main should refer to the memory allocated by the function get_vector.

#include <iostream>
#include <vector>
#include <string>

using namespace std;

vector<double>& get_vector()
{
  cout << "Enter function" << endl;

  vector<double> asd;
  asd.push_back(10.);

  cout << "Exit function" << endl;

  return asd;
}


int main() {
  vector<double>& asd = get_vector();
  cout << "Vector received" << endl;
  cout << asd[0] << endl;
}

Another point is that when compiling it with g++ I get a warning saying warning: reference to local variable ‘asd’ returned. I imagine this is something very bad... could someone tell me what is the problem or give me some link where I can find an explanation to that?

Thank you

http://stackoverflow.com/questions/4643713/c-returning-reference-to-local-variable — Undefined Behaviour, Mar 24 '17 at 08:03
The vector `asd` gets destroyed when the enclosing scope ends (function `get_vector`). So in your main function after the call to `get_vector` returns there is no vector. You are left with a reference to nowhere. — Richard Critten, Mar 24 '17 at 08:04
Ok... thank you.... that is obvious now that you told me! :) Thank you! — Riccardo Petraglia, Mar 24 '17 at 08:06
And this also explain why I found around in internet that it works if I pass the reference to the vector as input of the function.... :) — Riccardo Petraglia, Mar 24 '17 at 08:07

Create and return a vector by reference

0 Answers0