A C compiler is a software program that translates human-readable C source code into machine-readable executable code that can be run on a computer. A C compiler reads the source code, compiles it into assembly code, and then translates the assembly code into machine code that can be executed by the computer's CPU.
The C compiler performs several tasks, such as parsing the source code, checking for syntax errors, generating assembly code, optimizing the code for better performance, and generating object files. The object files are then linked with libraries and other object files to create the final executable program.
Here are the main steps involved in the C compilation process:
Preprocessing: The C preprocessor is run on the source code to perform macro expansion, file inclusion, and conditional compilation. This step generates a preprocessed source code that is used as input to the compiler.The preprocessor directives start with a # symbol, such as "#include" and "#define"
. The preprocessed code is then passed to the compiler.
Compilation: The compiler reads the preprocessed source code and translates it into assembly code, which is a low-level representation of the source code. The assembly code is then translated into object code, which is a machine-readable binary format that contains instructions and data.
Linking: The linker takes one or more object files generated by the compiler and combines them with libraries to create an executable file. The linker resolves external symbols, such as function calls and global variables, and generates the final machine code. The linker also performs address relocation and symbol binding, which are necessary for linking object files with different memory layouts.
Loading and execution: The operating system loads the executable file into memory and prepares it for execution. The loader allocates memory for the code and data segments, resolves dynamic linking, and initializes the program's environment, such as the stack and the heap. The CPU then executes the machine code, which performs the desired operations, such as input/output, computation, and memory manipulation.
There are several C compilers available, both open-source and commercial, that can compile C code into machine-readable executable code. Here are some popular C compilers and their details:
GCC (GNU Compiler Collection): GCC is a free and open-source compiler that supports many programming languages, including C. GCC is widely used on many platforms, such as Linux, macOS, and Windows. GCC includes several optimization levels, debugging options, and architecture-specific features.
Clang: Clang is a C compiler developed by Apple that is designed for performance, compatibility, and standards compliance. Clang is also free and open-source and is widely used on macOS and Linux platforms. Clang has a modular architecture that enables advanced code analysis and error reporting.
Microsoft Visual C++: Microsoft Visual C++ is a commercial C++ compiler that supports C language as well. It is part of the Visual Studio development environment and runs on the Windows operating system. Visual C++ supports many features, such as inline assembly, structured exception handling, and Windows-specific APIs.
Turbo C++: Turbo C++ is an old compiler that was popular in the early days of C programming. It is a free and lightweight compiler that supports the C language and is easy to use for beginners. Turbo C++ runs on the DOS operating system and requires an emulator to run on modern systems.
Tiny C Compiler (TCC): TCC is a small and fast C compiler that supports many features, such as cross-compilation, dynamic linking, and runtime code generation. TCC is free and open-source and runs on many platforms, such as Linux, macOS, and Windows. TCC is often used for embedded systems, scripting languages, and educational purposes.
These are just a few examples of C compilers available. The choice of the compiler depends on the specific requirements of the project, such as performance, compatibility, standards compliance, and platform support.
In summary, C compilation is the process of translating human-readable C source code into machine-readable executable code that can be run on a computer. The compilation process involves several steps, such as preprocessing, compilation, linking, loading, and execution, that convert the source code into an executable program.