The Compiler

The C compiler translates C-source-code into machine code.

The Compiler translates each source file into an object file also known as a module.

If there are more that 1 object files, these are then linked by the linker which outputs a executable.

The executable is what we normally run as a program in the system.

The Translation Phases

The compilation takes place in 8 steps.

Read Source
- Convert the File Charset into Source Charset if necessary
- Convert end-of-line indicators to newline chars if needed
- Trigraphs are converted to their single char versions
- Digraphs are left as they are.
whenever a backslash is followed by a newline character, it is deleted
Source is Broken in Tokens.
- each Comment is converted into a space.
Preprocessor Directives are carried out and macro calls are expanded
It is the converted into the Execution Character Set
- all character and escape sequences in char constants and strings converted.
Adjacent String Literals are concatenated
Compiling Begins and the tokens are converted into Machine Code
The Linker is invoked
- it resolves references to external objects and functions
- generates the executable file
- External objects and functions should not be defined more than once

use make when you can. Assume you have a file, file.c, then:

make file

CFLAGS="-Wall" make file

use a makefile named “Makefile”:

CFLAGS=-Wall -g

clean:
  rm -f file