Install <unordered_set>

[projectUser]

I included #include <unordered_set> at the header and it's giving me this warning

error This file requires compiler and library support for the upcoming ISO C++ standard, C++0x. 
This support is currently experimental, and must be enabled with the -std=c++0x or -std=gnu++0x compiler options.

Any idea on how to fix this?

[firedraco]

must be enabled with the -std=c++0x or -std=gnu++0x compiler options.

[projectUser]

ok thanks already got it

g++ -std=c++0x file.cpp -o file