Hello, I have been using the std::ifstream w/o issue except my data files have grown > 2GB, and as is well documented it is failing. I am on OS X 10.6 and I have my executable compiling/running as a x86_64 (64bit) executable. I read that boost supports a 64bit streamposition in boost::filesystem::ifstream. I have compiled boost using darwin ports (I should state I never specifically said anything about x86_64 during this compilation). I have re-run my program and I have the same problem (I use tellg to confirm the issue is the streamposition). My questions are: 1 - Does the boost ifstream in fact support large files? 2 - If 1) is true, then what specifically needs to be done to get this support? 3 - Unrelated, but what do the "-mt" and "-d" added to the dylib file name mean? (libboost_filesystem-mt-d.dylib) thanks! Lucas -- View this message in context: http://old.nabble.com/boost-filesystem%3A%3Aifstream-for-files-larger-than-2... Sent from the Boost - Users mailing list archive at Nabble.com.