The GNU C++ Iostream Library - Input Position

Repositioning an istream

Use these methods to control the current input position:

Method streampos istream::tellg ()

Return the current read position, so that you can save it and return to it later with istream::seekg .

Method istream& istream::seekg (streampos p)

Reset the input pointer (if the input device permits it) to p, usually the result of an earlier call to istream::tellg .

Method istream& istream::seekg (streamoff offset, ios::seek_dir ref)

Reset the input pointer (if the input device permits it) to offset characters from the beginning of the input, the current position, or the end of input. Specify how to interpret offset with one of these values for the second argument:

ios::beg

Interpret loc as an absolute offset from the beginning of the file.

ios::cur

Interpret loc as an offset relative to the current output position.

ios::end

Interpret loc as an offset from the current end of the output stream.