C++ arrays inizialization

Question

Try and execute this code:

https://code.sololearn.com/c1uONqAVZ5af/?ref=app

without Initializing arrDigits. You'll get a lot of random results, especially if you execute code several consecutive times.
Why? Shouldn't arrDigits be automatically initialized to all zeroes?

Answer 1

Seems it depends on sololearn compiler. Needs initialization manually. Good code by the way, easy to understand and follow.