cpp/io/clog

The global objects and  control output to a stream buffer of implementation-defined type (derived from std), associated with the standard C output stream stderr, but, unlike std/std, these streams are not automatically flushed and cout is not automatically tie'd with these streams.

These objects are guaranteed to be initialized during or before the first time an object of type std is constructed and are available for use in the constructors and destructors of static objects with ordered initialization (as long as is included before the object is defined).

Unless has been issued, it is safe to concurrently access these objects from multiple threads for both formatted and unformatted output.