update atomic

Author: lulongfei

atomic.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+#include <atomic>
+#include <thread>
+
+
+std::atomic<int> foo = 0;
+
+void set_foo(int x)
+{
+    foo = x;
+}
+
+void print_foo()
+{
+    while(foo == 0)
+    {
+        std::this_thread::yield();
+    }
+    std::cout << "foo: " << foo << std::endl;
+}
+
+
+int main()
+{
+    std::thread first(print_foo);
+    std::thread second(set_foo, 10);
+    first.join();
+    second.join();
+    return 0;
+}
+