boost::multi_array vs Range based for loop

gistfile1.cpp

#include <gtest/gtest.h>
#include <boost/multi_array.hpp>

TEST(MultiArrayTest, Fill) {
  boost::multi_array<int, 2> subject(boost::extents[20][10]);
  for (auto x : subject) {
    for (auto &y : x) {
      y = 10;
    }
  }
  EXPECT_EQ(10, subject[5][4]);
}

preffered:

for (auto &x : subject) {
  x = 10;
}

not to think about dimension.