C++ How to read in objects with a given offset?

Question

Now I have a file with many data in it. And I know the data I need begins at position (long)x and has a given size sizeof(y) How can I get this data?

Answer 1

Use the seek method:

ifstream strm;
strm.open ( ... );
strm.seekg (x);
strm.read (buffer, y);

Answer 2

You should use fseek() to change your "current position" in the file to the desired offset. So, if "f" is your FILE* variable and offset is the offset this is how the call should look like (modulo my leaky memory):

fseek(f, offset, SEEK_SET);