What is the difference between the C programming language and C programming under linux?

Question

What is the difference between the C programming language and C programming under Linux?

Are the syntax same in both them?

Or is the difference only when you execute the program?

Answer 1

The C language is governed by the ISO approved C standard and it does not take in to account the underlying platform on which you use C. So from the perspective of the language standard there is no difference, and a standard compliant program shall work correctly on both.

However in practical usage one needs to do platform specific things for ex: IPC mechanisms, multithreading, file access and so on which are specific to the platform, such functionality will vary from platform to platform because each will provide functionality specific to itself. Note that such functionality is not covered by the C language standard, so using it makes the program non portable across other platforms.

Answer 2

Linux is a platform that can be used for the development of programs and applications using languages such as C. The only thing is that its supposed to be is its simplicity and one's liking to a particular operating system. Otherwiswe there is no difference in the syntax. It is absolutely same.

Answer 3

There are languages and there are platforms. Popular languages are typically governed by standards (eg, ANSI). C is a programming language.

Linux, Windows, Android, etc, are platforms (or, specifically, operating systems). Each platform offers a set of libraries (API calls) that you can access to do different things on that platform. System/library calls for file system access, networking, specific windowing/GUI system, etc, can be different on different platforms. So knowing how to "write C on Linux" means you know C and you know a lot of Linux platform calls. Even different windowing systems under Linux can have different API calls.

There are also standards across platforms, such as POSIX, which work to make the library calls the same across different platforms. Although this doesn't deal with most of the disparity between GUI APIs.

Answer 4

The C language programming syntax is defined under the ISO C standard. The resulting execution depends on the compiler used to turn code into an executable program and the machine on which the compile runs (or at least the target architecture it runs for). The results from that compilation will depend on the use of the programming syntax (the code) against the interpretation of that code from the compiler. If the programmer restricts his programming habits to writing conformant C code excluding implementation-defined behavior or undefined behavior, it's resulting executable will behave identically on any platform.

Then you think of it as if there was roughly three "layers" of C implementation you could make: kernel programming, system programming and userspace programming.

Kernel programming is hardware-level programming and usually leverage implementation-defined behavior to interface the hardware world to the software world. They provide a C interface to system programmers. They are different from machine to machine and the architercture resulting from these implementation defines the difference between various OS (ex: window vs linux vs OsX vs MIT exokernel, etc).

System programmers leverage the kernel's (the system's) API to build C standard library (they define the implementation of higher level C standard functionnalities). Ex: glibc and the gnu c compiler (gcc) should be iso C conformant to unambiguous section of the C standard and defines the implementation of implementation-define AND undefined behavior. That layer of implementation is hardware independant (to some extend) since the kernel level constitute an hardware abstraction. But they handle resource from that abstraction layer (ex: RAM or writting to a file on the hard drive or sending a stream of data on an internet socket).

Userspace programmers code the programs that uses the standard API and the compilers to build "usable" pieces of software such as gnome-terminal or i3 windows tiling manager (I can't find an example a C code "user-friendly" running under windows from the top of my head...). Unless these software implementation resort to implementation-define code or undefined behavior code, it should be platform independent.

Answer 5

The answer is simple: There is no difference!

However each operating system has its own API. This API does not depend on the programming language.

Example: The "MessageBox()" function exists in Windows only, not in Linux. It is a Windows-Specific function (available in any programming language under Windows).

There are also some library functions that are named differently in Linux and in Windows.

One example would be the "stricmp()" function (Windows) that is named "strcasecmp()" under Linux. However this is not an issue of the C programming language but of the libraries (.H files and .SO files).

Answer 6

Different operating systems will have different APIs (Application programming interfaces) which can be libraries built for building application software for your specific OS. GNU/Linux has libraries specific to it such as sys/socket.h , linux.h , sys/types.h , etc.