How can I see the output of the Visual C++ preprocessor?

Question

I want to see the output of the Visual C++ Preprocessor on my code -- i.e., the equivalent of gcc -E. For the life of me, I cannot find the relevant compiler switch. How do I accomplish this?

score 46 · Answer 1 · edited Dec 27 '18 at 23:43

46

Project properties -> C/C++ -> Preprocessing -> Preprocess to a file: Yes (/P)

The files will be called .i and will be created in the build directory.

Also see the msdn page.

edited Dec 27 '18 at 23:43

Antonio

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answered Jan 23 '12 at 21:42

Xeo

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You can specify the preprocessor output file with the /Fi compiler parameter. You can also specify the output path only - just make sure the path ends with a trailing backslash. – MikeOnline Jan 18 '17 at 19:15
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@marsh: The files will be called .i and will be created in the build directory. – Daniel Jan 27 '17 at 16:36
Where is "Project properties"? Going to `Project` (top menu) > `Properties`, I can't find any `C/C++` menu item. – Iulian Onofrei Apr 22 '18 at 11:14
@IulianOnofrei right click on your project (not the solution) in the Solution Explorer window that's usually on the right of the screen and is what you use to navigate through your project. Once you right click, there should be an option called "Properties". That's the project properties. – Pro Q Jun 02 '18 at 01:17
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When I did this, I got `error MSB6001: Invalid command line switch for "CL.exe"` – Pro Q Jun 02 '18 at 01:22

score 23 · Accepted Answer · edited May 23 '17 at 12:34

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cl.exe, the command line interface to Microsoft Visual C++, has three different options for outputting the preprocessed file (hence the inconsistency in the previous responses about Visual C++):

/E: preprocess to stdout (similar to GCC's -E option)
/P: preprocess to file
/EP: preprocess to stdout without #line directives

(copied directly from https://stackoverflow.com/a/277362/3279)

edited May 23 '17 at 12:34

Community

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answered Jan 23 '12 at 21:45

shadyabhi

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Nice copy-paste without even a link to [the original answer](http://stackoverflow.com/a/277362/688659)... – gx_ Jun 26 '13 at 16:27
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I just did this, and this answer isn't complete. After setting /P, for file "foo.c" you need to look for the file "foo.i". (This may seem obvious, but you have to look in the right directories, and that depends on how your project files are configured). – Ira Baxter Aug 24 '14 at 08:38

How can I see the output of the Visual C++ preprocessor?

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