warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions]

struct test{
int a=1111111;

}test;

vincentdeMacBook-Air:datasturte vincent$ g++ struct.cpp -o structpp
struct.cpp:4:6: warning: in-class initialization of non-static data member is a
      C++11 extension [-Wc++11-extensions]
int a=11111111;
     ^
1 warning generated.vin