I can print thread ID to console following way:
cout << "thread ID: " << std::this_thread::get_id() << endl;
Debug -> Windows -> Threads -> [ID column]
Debug -> Windows -> Threads
The standard says
An object of type thread::id provides a unique identifier for each thread of execution and a single distinct value for all thread objects that do not represent a thread of execution (30.3.1). Each thread of execution has an associated thread::id object that is not equal to the thread::id object of any other thread of execution and that is not equal to the thread::id object of any std::thread object that does not represent threads of execution.
thread::id shall be a trivially copyable class (Clause 9). The library may reuse the value of a thread::id of a terminated thread that can no longer be joined.
-- n4296; 126.96.36.199 [thread.thread.id]
It doesn't say that the ID is monotonically increasing, and it does permit thread IDs to be reused.
It's likely that you want the
native_handle, which will be the handle that the underlying implementation uses. This will correspond to the Windows thread handle, under MSVC. Whether these are monotonically increasing is a matter for your implementation's documentation.
The MSDN documentation for the
GetCurrentThreadId function suggests that the thread ID uniquely identifies a thread until it terminates; it doesn't say whether the IDs are monotonically increasing, and the implication of that sentence appears to be that they may be reused.
In summary, the C++ standard provides no guarantee about the values of thread IDs. If you want to guarantee this, you'll need to have each thread increment an atomic counter, or otherwise obtain a monotonically increasing value with appropriate synchronisation.