How to set up Windows sound loopback

Install  VB-audio virtual cable

When recording background music:
Sound | Playback | Set Cable Input as Default

Sound | Recording | Microphone Array | Properties | Listen to Cable Input

Sound | Recording | Cable Output | Properties | Listen to Headphone

In the recording app, set the mic to Cable Output as the input source.

This way the Cable Output will include both the background music from the computer and the sound from the microphone.

Eclipse Java autoformatter line wrapping settings

Uncheck Prefer wrapping outer expressions(...)

C++: Please very special attention to map element deletion when iterating it

The normal way doesn't work. You need to use this way:

for (auto it = m.cbegin(); it != m.cend() /* not hoisted */; /* no increment */)
{
  if (must_delete)
  {
    m.erase(it++);    // or "it = m.erase(it)" since C++11
  }
  else
  {
    ++it;
  }
}

C++ code should depend on tcmalloc

It can improve the performance by 30%

C++ Move Semantics

https://mbevin.wordpress.com/2012/11/20/move-semantics/