atomic_thread_fence is not a member of std

Compiling with:

g++ -std=c++0x -Wall -pthread test2.cc -o hello

I'm getting this error:

test2.cc: at开发者_Go百科omic_thread_fence is not a member of std

I am using g++ 4.5.2 in Ubuntu. What am I missing?

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Do you have the following in test2.cc?

#include <atomic>