Stream position type
 Type to represent positions in a stream.Objects of this class must support construction and conversion from int, and allow consistent conversions to/from streamoff objects, as well as the addition and subtraction of streamoff objects.
Another requirement is that two streampos objects must be able to be compared with == or != yielding a value convertible to bool, or be subtracted yielding an object of type streamoff.
It is a synonym of the instance of fpos with mbstate_t state type as template parameter.
See also
| fpos | Stream position class template (class template) | 
| streamoff | Stream offset type (type) | 
| streamsize | Stream size type (types) |