On 07/31/2009 03:12 PM, Patrick Dupre wrote: > Hello, > > I do observe abnormal results with my applications > > Moving from a 32 to 64 bits architecture, using, c, C++, perl, is > they something that I should be aware of ? like size of the > float, integer ? > > Thank. > In the C and C++ languages as implemented by GCC on Linux and other Unix systems use a policy called LP64 for 64-bit systems: char is 8 bits, short is 16 bits, int is 32 bits (always on 32 and 64 bit systems using LP64). long is 64-bits (on 64-bit systems, 32-bits on 32-bit systems) float is always 32-bits double is always 64-bits pointers are 64-bits on 64-bit systems, 32-bits on 32-bit systems. There are a number of programming gothchas that have been well documented. here is a pointer to some documents on HP (part of which I wrote) http://docs.hp.com/en/5966-9844/ch03s02.html But, beware, while Linux and Unix systems have adopted LP64 pretty universally, other systems use LLP64 and ILP64. The bottom line when writing programs is not to assume anything. Use types like int32_t, or int64_t for signed integrals, use size_t for sizes. That will generally be 32-bit on 32-bit systems and 64-bits on 64-bit systems. -- Jerry Feldman <gaf@xxxxxxx> Boston Linux and Unix PGP key id: 537C5846 PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB CA3B 4607 4319 537C 5846
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