How to write super-fast file-streaming code in C#?

Question

I have to split a huge file into many smaller files. Each of the destination files is defined by an offset and length as the number of bytes. I\'m using the following code:<

Answer 1

You shouldn't re-open the source file each time you do a copy, better open it once and pass the resulting BinaryReader to the copy function. Also, it might help if you order your seeks, so you don't make big jumps inside the file.

If the lengths aren't too big, you can also try to group several copy calls by grouping offsets that are near to each other and reading the whole block you need for them, for example:

offset = 1234, length = 34
offset = 1300, length = 40
offset = 1350, length = 1000

can be grouped to one read:

offset = 1234, length = 1074

Then you only have to "seek" in your buffer and can write the three new files from there without having to read again.