__int64 for GCC as a Preprocessor Option

Question

Usually Microsoft code uses __int64 which is not understood by GCC. I know I can write it as a macro like this:

#define __int64 long long

But I don't want to do this, due to code portability. I'm trying to give GCC the following Preprocessor Option:

-D__int64="long long"

I get the following error due to the space between the two long's:

gcc.exe: error: long: No such file or directory

How to fix it ?

You also need to compile with C99 standard or later. gcc -std=c99 — Lundin
– Lundin, Commented Jan 27, 2015 at 15:25
May I ask why you need an 64 bit int, I'm just curious why the 32 bit wouldn't be enough? — Code Guru
– Code Guru, Commented Jan 27, 2015 at 16:02
@HeshamEraqi That is not a valid reason, you're performance will go down because of using a larger register than you need. I do use 8 or 16 bit ints if my variable isn't going to need all that space. @ LưuVĩnhPhúc I think our friend only wanted to know his situation, no need to belittle him. — user2742371
– user2742371, Commented Jan 27, 2015 at 16:42
-D__int64="long\ long" (add more `\` before the space until it works) — Marc Glisse
– Marc Glisse, Commented Jan 27, 2015 at 23:48

unwind · Accepted Answer · 2015-01-27 15:20:37Z

6

You could use int64_t, the standard name for that type, but it will only work if the code does #include <stdint.h>, and that's perhaps hoping for too much.

Otherwise you could try to "sneak" in a typedef in some common header:

typedef long long __int64;

Perhaps doing that only if GCC is detected.

Fixing it "your way" should certainly be possible, it looks like some quoting issue.

answered Jan 27, 2015 at 15:20

unwind

402k64 gold badges492 silver badges620 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hesham Eraqi Over a year ago

Changing the code is not a preferred option in my situation. I tried different quoting combinations to "my way", and it didn't work.

Chris Dodd · Accepted Answer · 2015-01-27 16:22:06Z

3

Sounds like you have a double-eval issue if your example doesn't work. If you can't figure out why that is happening you can try using gcc's -include or -imacros option. You would create a new file gcc_extra_definess with the #defines you want to add, and call gcc -include gcc_extra_defines ... to get gcc to read that file and include it before reading the source file. This is a bit easier than a bunch of -D options for defining multiple things, particularly if you have quoting issues or want things other than macros.

answered Jan 27, 2015 at 16:22

Chris Dodd

127k14 gold badges150 silver badges243 bronze badges

Comments

Jens · Accepted Answer · 2015-01-27 15:37:45Z

2

Looks like a quoting problem caused by gcc seeing only

gcc ... -D__int64=long long

Can you show us the script or Makefile snippet you use? What shell is it?

answered Jan 27, 2015 at 15:37

Jens

73.3k16 gold badges134 silver badges186 bronze badges

Collectives™ on Stack Overflow

__int64 for GCC as a Preprocessor Option

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related