1
Compiler
.c cpp cc1 .o ld
C source
Preprocessor Compiler
Preprocessed
source
Linker
Object
files Executable
gcc
Preprocessor
•The first step is the preprocessor
•It handles any of the # directives
•For example, #include
•#include takes a file name argument, and
"pastes" that file into the current one
•If the filename is surrounded by <and >, it is
found in the include path (e.g., /usr/include)
•If it's in quotes, it looks in the current directory
#define
•#define is useful for declaring constants:
•Any PI in code is replaced with 3.14…
–Excludes PI within comments and string literals
•#define'd constants are true replacements:
#define PI 3.1415926535
#define BUFSIZE 1024
char buffer[BUFSIZE];
char buffer2[BUFSIZE + 16];
Executables
•What do we need to store?
–Code
–Data
–More?
•Agree on a common format (much like with
ID3 tags)
Older Executable Formats
•a.out (Assembler OUTput)
–Oldest UNIX format
–No longer commonly used
•COFF (Common Object File Format)
–Older UNIX Format
–No longer commonly used
