C++ Volatile Variables

http://en.wikipedia.org/wiki/Volatile_variable

http://www.cplusplus.com/forum/beginner/7762/

http://msdn.microsoft.com/en-us/library/12a04hfd%28v=vs.110%29.aspx

http://www.cl.cam.ac.uk/teaching/1112/CandC++/lectures/lecture4-land.pdf

http://stackoverflow.com/questions/386554/example-c-function-using-volatile-variables

http://stackoverflow.com/questions/2484980/why-is-volatile-not-considered-useful-in-multithreaded-c-or-c-programming

http://stackoverflow.com/questions/2444695/volatile-vs-mutable-in-c

http://en.wikipedia.org/wiki/Volatile_variable#In_C_and_C.2B.2B

http://software.intel.com/en-us/blogs/2007/11/30/volatile-almost-useless-for-multi-threaded-programming

http://www.drdobbs.com/cpp/volatile-the-multithreaded-programmers-b/184403766

To be short:

volatile is used to signify to the compiler not to optimize use of the variable that is declared volatile.

but it is not safe in multi-thread context.