Обсуждение: Preferred way to define 64-bit constants?
I just committed the patch to change XLogRecPtr into a 64-bit constant, and I did this in the patch: #define XLogSegmentsPerXLogId (0x100000000LL / XLOG_SEG_SIZE) But I started to wonder, is that LL representation the preferred way to define 64-bit integer constants? I thought it is, but now that I grep around, I don't see any constants like that in the source tree. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
On 24 June 2012 18:23, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote: > I just committed the patch to change XLogRecPtr into a 64-bit constant, and > I did this in the patch: > > #define XLogSegmentsPerXLogId (0x100000000LL / XLOG_SEG_SIZE) > > But I started to wonder, is that LL representation the preferred way to > define 64-bit integer constants? I thought it is, but now that I grep > around, I don't see any constants like that in the source tree. This looks to be a long long int literal. That's only specified in the C99 standard, as well as GNU C. It may very well not be a problem in practice, but I'm told that some very esoteric compilers could baulk at things like that. http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services
On sön, 2012-06-24 at 20:23 +0300, Heikki Linnakangas wrote: > I just committed the patch to change XLogRecPtr into a 64-bit constant, > and I did this in the patch: > > #define XLogSegmentsPerXLogId (0x100000000LL / XLOG_SEG_SIZE) > > But I started to wonder, is that LL representation the preferred way to > define 64-bit integer constants? I thought it is, but now that I grep > around, I don't see any constants like that in the source tree. See INT64CONST, UINT64CONST.
On 24.06.2012 21:34, Peter Eisentraut wrote: > On sön, 2012-06-24 at 20:23 +0300, Heikki Linnakangas wrote: >> I just committed the patch to change XLogRecPtr into a 64-bit constant, >> and I did this in the patch: >> >> #define XLogSegmentsPerXLogId (0x100000000LL / XLOG_SEG_SIZE) >> >> But I started to wonder, is that LL representation the preferred way to >> define 64-bit integer constants? I thought it is, but now that I grep >> around, I don't see any constants like that in the source tree. > > See INT64CONST, UINT64CONST. Thanks, fixed. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com