Preprocessor directives layout

• The preprocessor directive mark (#) MUST appear on the first column.
• Preprocessor directives following #if and #ifdef MUST be indented by one character:

            #ifndef DEV_BSIZE
            # ifdef BSIZE
            #  define DEV_BSIZE BSIZE
            # else /* !BSIZE */
            #  define DEV_BSIZE 4096
            # endif /* !BSIZE */
            #endif /* !DEV_BSIZE */
            

• As shown in the previous example, #else and #endif MUST be followed by a comment describing the corresponding initial condition.
• When a directive must span over multiple lines, escaped line breaks (\-newline) MUST appear on the same column. For this purposes, tabulations MUST be used.

  This is wrong: #define XFREE(Var) \ do \ { \ if (Var) \ free(Var); \ } \ while (0)

  This is correct:

            
  
            #define XFREE(Var)      \
              do                    \
              {                     \
                if (Var)            \
                  free(Var);        \
              }                     \
              while (0)
            
            

  
  Hint: use C-\ and C-u C-\, or M-i under Emacs.