0_0_29506499_12310.cpp: In function 'int main()': 0_0_29506499_12310.cpp:15:9: error: 'thread' is not a member of 'std' std::thread t1(Sum,a,b); ^ 0_0_29506499_12310.cpp:16:9: error: 't1' was not declared in this scope t1.join(); ^