利用sort进行排序

bool Comp( const Student &a, const Student &b ){     if( string(a.name) != string(b.name) )           return string(a.name) < string(b.name);     if( a.region != b.region )         return a.region < b.region;          if( a.id != b.id )         return a.id < b.id;}

 sort( vA.begin(), vA.end(), Comp );