What's the best way to declare an integer type which is always 4 byte on any platforms? I don't worry about certain device or old machines which has 16-bit int.
views:
2977answers:
8Just to note intN_t (and uintN_t) is optional in terms of standard. It is required to be defined if and only if the the system has types that meet the requirement.
KTC
2009-08-04 18:39:40
That's what you want though. If the code really requires a 32-bit int, and you try to compile it on a platform that doesn't support them, you *want* the compiler to punt back to the developer. Having it pick some other size and go on would be horrible.
T.E.D.
2009-08-04 19:20:35
Note that the header '`<inttypes.h>`' is explicitly documented to include the header '`<stdint.h>`' (this is not usual for C headers), but the '`<inttypes.h>`' header may be available where '`<stdint.h>`' is not and may be a better choice for portability. The '`<stdint.h>`' header is an invention of the standards committee, and was created so that free-standing implementations of C (as opposed to hosted implementations - normal ones) only have to support '`<stdint.h>`' and not necessarily '`<inttypes.h>`' too (it would also mean supporting '`<stdio.h>`', which is otherwise not necessary).
Jonathan Leffler
2009-08-04 19:28:40
+9
A:
Corey's answer is correct for "best", in my opinion, but a simple "int" will also work in practice (given that you're ignoring systems with 16-bit int). At this point, so much code depends on int being 32-bit that system vendors aren't going to change it.
(See also why long is 32-bit on lots of 64-bit systems and why we have "long long".)
One of the benefits of using int32_t, though, is that you're not perpetuating this problem!
Brooks Moses
2009-08-04 18:38:28
There's no need to “ignore systems with 16-bit int”, long is guaranteed to be at least 32-bit wide everywhere.
Bastien Léonard
2009-08-04 20:30:10
Right, but using "long" doesn't address the initial request, which is something that's exactly 32 bits. On (at least some flavors of) 64-bit Linux, for example, a long is 64 bits -- and that's something that's likely to come up in actual practice.
Brooks Moses
2009-08-04 23:16:51
A:
If stdint.h is not available for your system, make your own. I always have a file called "types.h" that have typedefs for all the signed/unsigned 8, 16, and 32 bit values.
Robert
2009-08-04 19:12:21
A:
also depending on your target platforms you can use autotools for your build system
it will see if stdint.h/inttypes.h exist and if they don't will create appropriate typedefs in a "config.h"
Spudd86
2009-08-04 19:21:46
+2
A:
You could hunt down a copy of Brian Gladman's brg_types.h if you don't have stdint.h.
brg_types.h will discover the sizes of the various integers on your platform and will create typedefs for the common sizes: 8, 16, 32 and 64 bits.
cfrantz
2009-08-04 19:48:30
A:
stdint.h is the obvious choice, but it's not necessarily available.
If you're using a portable library, it's possible that it already provides portable fixed-width integers.
For example, SDL has Sint32 (S is for “signed”), and GLib has gint32.
Bastien Léonard
2009-08-04 20:29:14
A:
I found this:
http://www.velocityreviews.com/forums/t282915-defining-a-32-bit-integer-on-every-platform.html
May be of help.
Seth Illgard
2009-09-01 15:14:24