The C Preprocessor
, a program
notionally run before the C compiler cc
. The preprocessor
s, arranges for #include
s to be included, deals with conditional compilation
via the #if
directives, and expands #define macro
s. However, sizeof
expanded in time to be used for conditional compilation.
By the "as if" rule, an ANSI C standard compiler need not in fact invoke a separate cpp program. If you need to run just the preprocessor, it may often be invoked using your C compiler's -E flag.