C++ - include unistd.h: why not cunistd?

Question

It's said that when including C header files in C++, the ".h" suffix should be removed and then add "c" at the beginning. For example, #include <cstdio> instead of #include <stdio.h> . But when I use sleep() in my code, #include <cunistd> does not work, but #include <unistd.h> works. Why not <cunistd> ?

Answer 1

您的算法对于大多数（所有？）标准C头是正确的，但unistd.h不是标准C的一部分，因此标准C ++反过来不包括它与其他c...头。

Answer 2

Because unistd.h never was part of the C language. It is part of the Operating System.

Answer 3

<unistd.h> ，代表unix标准标题，名称说明了一切。

Answer 4

unistd.h不是标准C的一部分。标准C ++ lib不包含其他c标头。