C++语句有不明白的地方,望各位大虾不吝赐教~

C++语句有不明白的地方,望各位大虾不吝赐教~
istream &operator>>(istream &is,user &ob)//?
{
is.getline(ob.g.no,10,'n');
is.getline(ob.g.name,16,'n');
is>>ob.g.no;//is>>ob.g.no
is>>ob.g.name;
is>>ob.g.sex;
is>>ob.g.position;
is>>ob.g.age;
is>>ob.g.date;
return is;
}
ostream &operator