How to pass using SendInput to Notepad?

Question

Keyboard

Good afternoon everyone, for a week now I have been trying to parse a program that would send button presses using WinAPI (user32.dll).
I tried a bunch of options and solutions.
www.cyberforum.ru/csharp-net/thread1296443.html
stackoverflow.com/questions/3644881/simulating-key...
www.cyberforum.ru/post8077788.html
But for reasons unknown to me, none of this works.
Those. it turns out the following, the notepad opens, the program works out with a bang, but not a single letter appears in the notepad itself.
Accordingly, I have the following questions:
1. Could this be because I'm using Win 10?
2. SendInput sent to notepad should print a letter, or did I misunderstand the principle?
Perhaps someone has a working code/solution/example. I will be glad for any help.

Answer 1

1. There is SPY ++, you can track all messages
2. It may be worth moving the focus to the input field or something like that.
I didn’t find work with focus on 3 links, maybe I didn’t look well.