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#include <iostream> 
#include <vector> 
#include <algorithm> 
 
using namespace std; 
 
inline ostream& operator <<( ostream& out, const vector< unsigned > & obj ) { 
   cout << "< "; 
   for( auto& p: obj ) 
      cout << p << " "; 
   return out << ">"; 
} 
 
void pow2( unsigned& i ) { i *= i; } 
 
int main( void ) { 
   const int examples = 4; 
   for( int i = 0; i < examples; i   ) { 
      unsigned ai[] = { 1, 2, 3, 4 , 5, 6, 7, 8, 9 }, 
           ni = sizeof( ai ) / sizeof( ai[ 0 ] );
      vector< unsigned > vi( ai, ai   ni ); 
      cout << vi; 
      switch( i ) { 
         case 0: 
            for_each( vi.begin(), vi.end(), pow2 ); 
            cout << " => " << vi << endl; 
            break; 
         case 1: 
            for_each( ai, ai   ni, pow2 ); 
            cout << " => " << vector< unsigned >( ai, ai   ni ) << endl; 
            break; 
         case 2: 
            for( auto& i : ai ) pow2( i ); 
            cout << " => " << vector< unsigned >( ai, ai   ni ) << endl; 
            break; 
         case 3: 
            for_each( vi.begin()   2, vi.end() - 2, pow2 ); 
            cout << " => " << vi << endl; 
            break; 
      } 
   } 
   system("pause");
   return 0;
}