Vectors of vectors string issue - c++

Question

i'm in a situation with a declaration of vector<vector<string>>. On windows it's ok i can declare this in a struct like vector<vector<string>>v={{"me","you"}} but on a linux machine..only errors so i must declare it after the struct initialization but how because mystruct.vec[0]={"me","you"} gives me a segmentation fault. Any sugestions please?

Answer 1

This program on gcc 4.7.2 works just fine:
#include <vector>
#include <string>
#include <utility>
#include <iostream>
using ::std::vector;
using ::std::string;
using ::std::move;
vector<vector<string>> foo()
{
vector<vector<string>>v={{"me","you"}};
return move(v);
}
int main()
{
using ::std::cout;
cout << "{\n";
for (auto &i: foo()) {
cout << " {\n";
for (auto &o: i) {
cout << " \"" << o << "\",\n";
}
cout << " },\n";
}
cout << "}\n";
return 0;
}
It produces this output:
$ /tmp/a.out
{
{
"me",
"you",
},
}
I think your problem is either an old compiler or that you have some other problem in some other place in your code.
I used this command line to compile:
$ g++ -std=gnu++0x -march=native -mtune=native -Ofast -Wall -Wextra vvstr.cpp
And my g++ gives this as a version:
$ g++ --version
g++ (GCC) 4.7.2 20121109 (Red Hat 4.7.2-8)
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
This page tells you which version of gcc has which C++ feature:
http://gcc.gnu.org/projects/cxx0x.html

Answer 2

If you are using GCC, them you need a version that supports this C++11 initialization feature, and then you need to tell the compiler to compile in C++11 mode by passing it the -std=c++0x flag (or =std=c++11 for the 4.7 series). See this demo, compiled with GCC 4.7.2:
#include <vector>
#include <string>
int main()
{
std::vector<std::vector<std::string>> v = {{"me","you"}};
}