Yes, an operating system can be written in C++ language only. In fact, many popular operating systems, such as Windows, Linux, and macOS, are written in C++.

C++ is a powerful and versatile language that is well-suited for writing operating systems. It is a compiled language, which means that the code is converted into machine code before it is executed. This makes C++ programs faster and more efficient than interpreted languages, such as Python and JavaScript.

C++ is also a statically typed language, which means that the types of variables and expressions are known at compile time. This helps to prevent errors and makes code more maintainable.

However, writing an operating system in C++ is a challenging task. It requires a deep understanding of the operating system concepts and the C++ language. It is also important to use good coding practices to ensure that the code is reliable and efficient.

If you are interested in writing an operating system in C++, there are many resources available online and in libraries. There are also many open source operating system projects that you can contribute to.

Here are some examples of operating systems written in C++:

• Windows NT
• Linux
• macOS
• FreeBSD
• ReactOS
• Haiku
• MINIX