Why is C used as the main programming language for operating systems? [closed]

Question

I was wondering why the programming language C is used for programming operating systems. What advantages does it have over other languages in OS development?

Answer 1

C is the language most like the machine code while still maintaining portability between different architectures.

Here are some features of C that are not seen in many other languages that make it suitable for OS developement:

• Direct memory access. Memory management is left to the programmer and therefore is an advantage in OS development where practically all things useful involve directly manipulating areas of RAM. Examples included Memory mapped IO, DMA controllers, page tables, etc. If these things cannot be directly represented by C structures, they can at least be accessed with C pointers.
• No runtime dependencies. Unlike C++, Java, C# and others, C has absolutely no runtime dependencies. It doesn't expect a memory manager, it doesn't expect process management, the only runtime dependency it has is that something calls the main() function. That means that you can write a C program that runs directly on hardware without expecting some kind of memory manager or input or output layer. This of course means that you have to implement your own, but nonetheless this is possible unlike in other languages. Much of the standard library doesn't require an operating system (ie string.h), while those parts that do can be implemented minimally by the programmer in OS development.
• Efficient byte-level manipulation. C is perfectly suitable at efficient byte level manipulation. That is, copying data to different areas, flipping bits around, and processing data in small amounts. While this is more tedious for the programmer, it is much more efficient both in usage of RAM and in processing time, which is essential in Operating Systems.
• All C code has a direct 1-1 translation to machine code that is easily understandable. As a result, C has no built in complicated data structures like trees or hash tables. This must be implemented by the programmer, the premise behind this being that the programmer should be able to see any C code and know exactly what it does in hardware. This doesnt occur in other languages like Python for example that has things such as the "Dictionary" datatype whose backend implementation is not necessarily known to the programmer. The C (and UNIX) philosophy is that the programmer knows better than the language, and this makes it very suitable for fine tuning details in OS and systems development, with the obvious downside of not having convenient structures built in.

Answer 2

C, as being a middle level language, provides high level constructs while still providing low level details that are closer to assembly language, and hence, the system. Because of this, using C is fairly easy in OS development. This is one of the primary reasons why it is the most commonly used: Because the C programming language was originally designed for system level and embedded software development.