C++ way of setting file position for file sizes larger than 32-bits? - C++ - tribe.net Tribe.net. Local Connections Re: C++ way of setting file position for file sizes larger than 32-bits? Hypno http://CPP.tribe.net/thread/5627843f-1135-4e23-97ef-11fc13a693a1#b0995a48-9613-4063-9582-acdacc3003e6 2006-11-08T07:55:04Z 2006-11-08T07:55:04Z I can't speak for other platforms but there is fsetpos() which I think is standard. I don't know that it does a clear and you may be on your own for that. This is Windows specific but when dealing with huge files under Windows I use MapViewOfFile()/UnmapViewofFile() which memory map a window into your file in multiples of SYSTEM_INFO.dwAllocationGranularity using the system's virtual memory functions. Hypno 2006-11-08T07:55:04Z C++ way of setting file position for file sizes larger than 32-bits? John Michael http://CPP.tribe.net/thread/5627843f-1135-4e23-97ef-11fc13a693a1#41813685-1e0d-468e-b2cf-4e9532096a24 2006-11-07T19:48:45Z 2006-11-07T19:48:45Z Hello, all ... I need to create a file and set it to a specific size (the idea being that there is another thread that uses std::ofstream::seekp() to write blocks to the file as they arrive off of the network, likely out of order, so if the 10th block of the file arrives before the 1st, I need to be able to handle it). The thing is, std::ofstream::seekp() doesn't seem to allow me to seek past the end of the file and set the file position there e.g. it sets the failbit true if I try. In C, I used to do this with feek(), so I could code something like this: fseek( pFile, 10000000, SEEK_SET ); // makes the file 10000000 bytes long if it was shorter before ... but fseek() expects a long for the seek position, and this is 2006, where a long isn't big enough (files could be much larger than 4G). I have to do this in a portable way (Windows and Mac OSX / *nix). Ideas? Regards, John, looking for a simple solution Falling You - exploring the beauty of voice and sound http://www.fallingyou.com John Michael 2006-11-07T19:48:45Z