The cin object, an instance of the istream class (in the <istream> library), can input characters from the console and convert them to the numeric form you specify. The ifstream class (in the <ifstream> library) will also allow you to input characters from a file and convert them to numeric form. As with outputting streams, you can use the stream classes with a string buffer so that you can convert from a string object to a numeric value.
The basic_istringstream class (in the <sstream> library) is derived from the basic_istream class, so you can create stream objects and extract items (numbers and strings) from these objects. The class provides this stream interface on a string object (the typedef ...
