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Re: How are __LITTLE_ENDIAN__ and __BIG_ENDIAN__ defined?

FYI, you can get a dump of everything that the compiler will #define for you (independent of what your code defines) by typing the following in a Terminal window:

cpp -E -dM /dev/null

Regards,

Matthew Formica
Developer Tools & Cocoa Evangelist
email@hidden

On Nov 16, 2005, at 7:49 AM, Clark Cox wrote:

On 11/16/05, Sean McBride <email@hidden> wrote: 
On 2005-11-15 16:27, Eric Albert said:

Also, since only one of them is defined would it be better to use
#if as I did above or should I use #ifdef?


In general, I prefer #if to #ifdef just because that protects you if
someone writes code like this:

#if __LITTLE_ENDIAN__
#define __BIG_ENDIAN__ 0
#endif

OTOH, some compilers, like CodeWarrior, will (optionally of course) give
a warning using an undefined macro in an #if test:

Warning : undefined macro '__LITTLE_ENDIAN__' used in #if or #elif conditional
HelloWorld.c line 11 #if __LITTLE_ENDIAN__

I'm not a language lawyer, so I'm not sure if it's defined behaviour to
do an #if test on an undefined macro. No doubt someone will pipe up. :) 

No doubt :)

Yes, it is well defined.
"#if UNDEFINED_MACRO"

is the same as:

"#if 0"

--
Clark S. Cox III
email@hidden
http://clarkcox3.livejournal.com/
http://homepage.mac.com/clarkcox3/
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References: 
 >How are __LITTLE_ENDIAN__ and __BIG_ENDIAN__ defined? (From: Dave Thorup <email@hidden>)
 >Re: How are __LITTLE_ENDIAN__ and __BIG_ENDIAN__ defined? (From: Eric Albert <email@hidden>)
 >Re: How are __LITTLE_ENDIAN__ and __BIG_ENDIAN__ defined? (From: "Sean McBride" <email@hidden>)
 >Re: How are __LITTLE_ENDIAN__ and __BIG_ENDIAN__ defined? (From: Clark Cox <email@hidden>)



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