Preprocessor Options
The following options are accepted by the preprocessor:
-C
-C
Using the -Coption prevents the preprocessor from stripping comments. See the description of cpp in the cpp(1) manpage for details.
-dM
-dM
When -dMis present, instead of normal preprocessor output the compiler lists the #define directives it encounters as it preprocesses the file, thus providing a list of all macros that are in effect at the start of the compilation. The -dMoption requires that -Por -Ealso be specified.
A common use of this option is to determine the compiler's predefined macros. For example:
touch foo.c ; cc -E -dM foo.c
-Dname
-Dname[=def]
name is the symbol name that is defined for the preprocessor.
def is the definition of the symbol name (name).
The -Dnameoption defines a symbol name (name) to the preprocessor, as if defined by the preprocessing directive#define.
If no definition (def) is given, the name is defined as 1.
NOTE: __ia64 and __HP_aCC are defined automatically.
Example:
The following example defines the preprocessor symbol DEBUGFLAG and gives it the value 1.
aCC -DDEBUGFLAG file.C
The following program uses this symbol:
#include <iostream.h> int main(){
int i, j; #ifdef DEBUGFLAG int call_count=0; #endif
/* ... */
}
-E
-E
Using the -Eoption runs only the preprocessor on the named C++ files and sends the result to standard output (stdout).
An exception to this rule is when-Eis used with +Make[d] option, the only output is the make dependency information. Unlike the -Poption, the output of -Econtains #line entries indicating the original file and line numbers.
Redirecting Output From This Option
Use the -.suffixoption to redirect the output of this option.
