# Preprocessor Options

This section contains descriptions for compiler options that pertain to preprocessing.

Parent topic: Compiler Options

- A, QA
  Specifies an identifier for an assertion.
- B
  Specifies a directory that can be used to find include files, libraries, and executables.
- C
  Places comments in preprocessed source output.
- D
  Defines a macro name that can be associated with an optional value.
- dD, QdD
  Same as option -dM, but outputs #define directives in preprocessed source.
- dM, QdM
  Tells the compiler to output macro definitions in effect after preprocessing.
- dN, QdN
  Same as option -dD, but output #define directives contain only macro names.
- E
  Causes the preprocessor to send output to stdout.
- EP
  Causes the preprocessor to send output to stdout, omitting #line directives.
- FI
  Tells the preprocessor to include a specified file name as the header file.
- gcc, gcc-sys
  Determines whether certain GNU macros are defined or undefined.
- gcc-include-dir
  Controls whether the gcc-specific include directory is put into the system include path.
- H, QH
  Tells the compiler to display the include file order and continue compilation.
- I
  Specifies an additional directory to search for include files.
- I-
  Splits the include path.
- icc, Qicl
  Determines whether certain Intel®-specific compiler macros are defined or undefined.
- idirafter
  Adds a directory to the second include file search path.
- imacros
  Allows a header to be specified that is included in front of the other headers in the translation unit.
- iprefix
  Lets you indicate the prefix for referencing directories that contain header files.
- iquote
  Adds a directory to the front of the include file search path for files included with quotes but not brackets.
- isystem
  Specifies a directory to add to the start of the system include path.
- iwithprefix
  Appends a directory to the prefix passed in by -iprefix and puts it on the include search path at the end of the include directories.
- iwithprefixbefore
  Similar to -iwithprefix except the include directory is placed in the same place as -I command-line include directories.
- Kc++, TP
  Tells the compiler to process all source or unrecognized file types as C++ source files. This is a deprecated option that may be removed in a future release.
- M, QM
  Tells the compiler to generate makefile dependency lines for each source file.
- MD, QMD
  Preprocess and compile, generating output file containing dependency information ending with extension .d.
- MF, QMF
  Tells the compiler to generate makefile dependency information in a file.
- MG, QMG
  Tells the compiler to generate makefile dependency lines for each source file.
- MM, QMM
  Tells the compiler to generate makefile dependency lines for each source file.
- MMD, QMMD
  Tells the compiler to generate an output file containing dependency information.
- MP
  Tells the compiler to add a phony target for each dependency.
- MQ
  Changes the default target rule for dependency generation.
- MT, QMT
  Changes the default target rule for dependency generation.
- nostdinc++
  Do not search for header files in the standard directories for C++, but search the other standard directories.
- P
  Tells the compiler to stop the compilation process and write the results to a file.
- pragma-optimization-level
  Specifies which interpretation of the optimization_level pragma should be used if no prefix is specified.
- u (Windows*)
  Disables all predefined macros and assertions.
- U
  Undefines any definition currently in effect for the specified macro.
- undef
  Disables all predefined macros.
- X
  Removes standard directories from the include file search path.