std::basic_istream<CharT,Traits>::tellg
Min standard notice:
Returns input position indicator of the current associated streambuf object.
# Declarations
pos_type tellg();
# Return value
The current position of the get pointer on success, pos_type(-1) on failure.
# Example
#include <iostream>
#include <sstream>
#include <string>
int main()
{
std::string str = "Hello, world";
std::istringstream in(str);
std::string word;
in >> word;
std::cout << "After reading the word \"" << word
<< "\" tellg() returns " << in.tellg() << '\n';
}