If I master C well, can I write my own OS for my Wishlist?

Question

C++ / C#

Well, I think the question is pretty clear. Just in case, I want to clarify that I'm talking about ordinary C, and not about sharp or pluses.
And at the same time I'll ask one more question: having mastered C, can I write a virus (or something like that) that will give me access to the computer data of an extremely far-sighted user? The question is purely theoretical, honestly.
The fact that for such purposes acre C, you need to know and a bunch of other things, I do not deny this, but you also need to know with what help these goals can be realized, and in this question I ask how C shows themselves as such a tool. Should have explained this earlier, sorry.

Answer 1

And at the same time I'll ask one more question: having mastered C, can I write a virus (or something like that) that will give me access to the computer data of an extremely far-sighted user? The question is purely theoretical, honestly.

It's not related to the programming language.
In our student years, we wrote Trojan viruses quite successfully for ourselves both in Pascal and in assembler.
It is not the knowledge of the language that is important, but the knowledge of the operating system - what and where to implement there.
This is different knowledge. Completely different.
You don't think that any programmer can easily write such a virus, do you?
But the programmer obviously knows the programming language.
But he does not know the internal structure of the OS, because he specializes in something else.
That's why it can't.
C is not that complicated a programming language.
You exaggerate the knowledge of the language.
And you are seriously downplaying the need to know the system.
Namely, there - in the system - there is a snag.
For comparison:
You can learn a language in a week . The system - will have to dig for months , if not years .

Answer 2

If I master C well, can I write my own OP for my Wishlist?

If you are good at C, you will have a good knowledge of the syntax of the C language. No more.
Knowledge of the PC device, from the knowledge of C you will not appear.
Add to the above the device of the target OS, the rules for working in it, the services available in the target OS, etc.
Here even *.bat can handle it, you don't have to go after yourself.

Answer 3

Purely theoretically, a virus can be written on almost anything.
But it is important to understand that a virus infects the operating system, not the source code.
Therefore, you need to understand exactly how the operating system works in order to break its security and exploit vulnerabilities.

Answer 4

I would not recommend you do this!