Hello, This isn't really a compiler bug, but it's something which the manual doesn't describe too well so I thought I would point this out.
This page of the manual: http://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html#Common-Predefined-Macros says this: " You should use these macros for testing like this: /* Test for a little-endian machine */ #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ " ... except you shouldn't ! To test for a little-endian machine you do this; #include <endian.h> #if __BYTE_ORDER == __LITTLE_ENDIAN I hope this is helpful. Keep up the great work! Regards, Chris My test: #include <iostream> int main() { #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ std::cout << "small end first\n"; #endif #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ std::cout << "big end first\n"; #endif return 0; } Output: small end first big end first gcc -v Using built-in specs. Target: x86_64-pc-linux-gnu Configured with: /var/tmp/portage/sys-devel/gcc-4.4.5/work/gcc-4.4.5/configure --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.4.5 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.4.5/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.5 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.5/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.5/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.4.5/include/g++-v4 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec --disable-fixed-point --without-ppl --without-cloog --enable-nls --without-included-gettext --with-system-zlib --disable-werror --enable-secureplt --enable-multilib --enable-libmudflap --disable-libssp --enable-libgomp --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.4.5/python --enable-checking=release --enable-java-awt=gtk --enable-objc-gc --enable-languages=c,c++,java,objc,obj-c++,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.4.5 p1.2, pie-0.4.5' Thread model: posix gcc version 4.4.5 (Gentoo 4.4.5 p1.2, pie-0.4.5) -- "They say great science is built on the shoulders of giants - not here. At Aperture we do all our science from scratch; no hand holding." - Cave Johnson, CEO Aperture Science. Follow me on twitter: @zeonglow