GCC - How to get an executable file?

In the early 1970s, Dennis Ritchie developed the C programming language as an improvement of B. B by Ken Thompson was also a modification based on BCPL system language.?Both were Bell Labs employees leading the language implementation for the Unix operating system.

Despite C already had a compiler, in the middle 1980s GCC by Richard Stallman came out as a free, best, and faster option than proprietary technology. It was developed over C, but as it became popular other developers started using it in other languages such as C++, Objective C, and Fortran, this is the reason why GCC change the meaning of its initials from GNU C Compiler to GNU Compiler Collection.

GCC process for C

GCC compiles a C program into an executable in 4 steps as follows:

1. Pre-processing: via the GNU C Preprocessor, includes the headers (#include) and expands the macros (#define). The result is an intermediate file *.i that contains the expanded source code.

  $ ls
  filename.c
  $ gcc -E filename.c > filename.i
  $ ls
  filename.c    filename.i
  $   
            

2. Compilation: The compiler compiles the preprocessed source code into assembly code. The -S option specifies to produce assembly code, instead of object code. The resultant assembly file is *.s .

  
  $ ls
  filename.c    filename.i
  $ gcc -S filename.i
  $ ls
  filename.c    filename.i    filename.s
  $   
           

3. Assembly: The assembler converts the assembly code into machine code in the object file *.o with the option -c .

  
  $ ls
  filename.c    filename.i    filename.s
  $ gcc -c filename.i
  $ ls
  filename.c    filename.i    filename.o    filename.s
  $   
            

4. Linker: Finally, the linker links the object code with the library code to produce an executable file *.exe or *.out. An executable file requires external resources (system functions, C run-time libraries etc.) If the purpose is to merge object files, gcc can do it with the comand `ld `. If there is no need to type the command directly, the entire linking process is handled by?gcc?when invoked as follows:

  
  $ ls
  filename.c    filename.i    filename.o    filename.s
  $ gcc filename.s -o filename.exe
  $ ls
  filename.c    filename.exe    filename.i    filename.o    filename.s
  $
         

Example:

Run a C file (5-print_numbers.c) through the preprocessor, compiler, assembly, and linker and save the result. Show the content of each file.

gcc -E 5-print_numbers.c > 5-print_numbers.i
gcc 5-print_numbers -S
gcc 5-print_numbers -c
gcc 5-print_numbers -o 5-print_numbers.exe
        

Expanded source code file (*.i):

Assembly code file (*.s):

Object code file (*.o):

Executable code file (*.exe):

This blog entry explained and exampled the compilation process steps of a C program using GCC such as, preprocessing, compilation, assembly, and linking. Thanks for reading!