Which C compiler is used in Linux?

The most important software-development tool in Linux is GCC — the GNU C and C++ compiler. In fact, GCC can compile three languages: C, C++, and Objective-C (a language that adds object-oriented programming capabilities to C). You use the same gcc command to compile and link both C and C++ source files.

Does Ubuntu come with AC compiler?

gcc is one of the most widely used C compilers. GCC compiler comes pre installed with ubuntu operating system. To compile your c program, open command prompt and go to your current working directory where you saved your HelloWorld.