What is the difference between string, cstring and string.h libraries?

Question

C++ / C#

I would like to know what is the main difference between them? Why is there no one library, why multiply them when they are almost different. Coded on Visual Studio, I know that VS doesn't care about standards. Can you answer the question or send the source? Searched the internet and didn't find a definitive answer.

Answer 1

Searched the internet and didn't find a definitive answer.

Badly searched, in the issue in the first links - an authoritative IT resource explains:
https://otvet.mail.ru/question/86060856