Getting the current read position.
Declared in <bslstl_istringstream.h>
pos_type
tellg();If fail() is not false, returns pos_type(-1) to indicate failure. Otherwise returns rdbuf()->pubseekoff(0,cur,in).
This function does not count the number of characters extracted, if any, and therefore does not affect the next call to gcount(). At variance with putback, unget and seekg, eofbit is not cleared first.
A file position object.