protected virtual member function
<streambuf> <iostream>
pos_type seekoff (off_type off, ios_base::seekdir way,
ios_base::openmode which = ios_base::in | ios_base::out);Set internal position pointer to relative position
Virtual function called by the public member function pubseekoff to alter the stream positions of one or more of the controlled sequences in a specific way for each derived class.
Its default behavior in basic_streambuf is to do nothing and return -1, but derived classes shall override this behavior to alter the internal pointers appropriately: both basic_filebuf and basic_stringbuf override this virtual member function to set the internal pointer specified by which to a position offset off relative to the direction specified by way.
Parameters
- off
- Offset value, relative to the way parameter.
Member type off_type is determined by the character traits: generally, it is an alias of the signed integral type streamoff.
- way
- Object of type ios_base::seekdir. It may take any of the following constant values:
| value | offset is relative to... |
|---|
| ios_base::beg | beginning of the stream buffer |
| ios_base::cur | current position in the stream buffer |
| ios_base::end | end of the stream buffer |
- which
- Generally used to determine the position on which of the controlled sequences shall be modified: the input sequence, the output sequence, or both. It is an object of type ios_base::openmode that, for this function, may take any combination of the following significant constant values:
| value | position pointer affected |
|---|
| ios_base::in | Modify current position in controlled input sequence |
| ios_base::out | Modify current position in controlled output sequence |
Return Value
Returns pos_type(off_type(-1)).
Member type pos_type is determined by the character traits: generally, it is an fpos type (such as streampos) that can be converted to/from integral types.
Data races
Introduces no data races, but overriden versions in derived classes may.
Exception safety
No-throw guarantee: this default definition never throws exceptions.