c++ - WriteFileGather - What is the way to write huge files(bigger than 4 GB)? -

i using windwos xp , want append data (about 4 mb each time) file. using 'writefilegather', increase offset's value of overlapped struct time. since the system call 32 bit, offset value(dword) can not exceed 4gb value.

code sample:

large_integer size; if (!getfilesizeex(_hfile, &size)) {     return; } overlapped.offset = size.quadpart; 

using ftell , fseek not working me. apparently, 'writefilegather' requires overlapped.offset value assigned.

what way exceed 4g limit?

writefilegather takes overlapped structure gets offset within file @ writing starts. offset split high , low doubleword (offset , offsethigh), it's 64-bit offset.

so, if want use writefilegather (personally, wouldn't), no hindrance. cannot write more 4gb in 1 go (but wouldn't want anyway!), though total file length or offset file can lot larger that.