fig21_30.cpp

《c＋＋大学教程》源码

// Fig. 21.30: fig21_30.cpp
// Mathematical algorithms of the standard library.
#include <iostream>

using std::cout;
using std::endl;

#include <algorithm>  // algorithm definitions  
#include <numeric>    // accumulate is defined here
#include <vector>

bool greater9( int );
void outputSquare( int );
int calculateCube( int );

int main()
{
   const int SIZE = 10;
   int a1[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

   std::vector< int > v( a1, a1 + SIZE );
   std::ostream_iterator< int > output( cout, " " );

   cout << "Vector v before random_shuffle: ";
   std::copy( v.begin(), v.end(), output );

   // shuffle elements of v
   std::random_shuffle( v.begin(), v.end() );

   cout << "\nVector v after random_shuffle: ";
   std::copy( v.begin(), v.end(), output );

   int a2[] = { 100, 2, 8, 1, 50, 3, 8, 8, 9, 10 };
   std::vector< int > v2( a2, a2 + SIZE );
   
   cout << "\n\nVector v2 contains: ";
   std::copy( v2.begin(), v2.end(), output );
 
   // count number of elements in v2 with value 8
   int result = std::count( v2.begin(), v2.end(), 8 );

   std::cout << "\nNumber of elements matching 8: " << result;
 
   // count number of elements in v2 that are greater than 9
   result = std::count_if( v2.begin(), v2.end(), greater9 );

   cout << "\nNumber of elements greater than 9: " << result;

   // locate minimum element in v2
   cout << "\n\nMinimum element in Vector v2 is: "
        << *( std::min_element( v2.begin(), v2.end() ) );

   // locate maximum element in v2
   cout << "\nMaximum element in Vector v2 is: "
        << *( std::max_element( v2.begin(), v2.end() ) );

   // calculate sum of elements in v
   cout << "\n\nThe total of the elements in Vector v is: "
        << std::accumulate( v.begin(), v.end(), 0 );

   cout << "\n\nThe square of every integer in Vector v is:\n";

   // output square of every element in v
   std::for_each( v.begin(), v.end(), outputSquare );

   std::vector< int > cubes( SIZE );
   
   // calculate cube of each element in v; 
   // place results in cubes
   std::transform( 
      v.begin(), v.end(), cubes.begin(), calculateCube );

   cout << "\n\nThe cube of every integer in Vector v is:\n";
   std::copy( cubes.begin(), cubes.end(), output );

   cout << endl;

   return 0;

} // end main

// determine whether argument is greater than 9
bool greater9( int value ) 
{ 
   return value > 9; 

} // end function greater9

// output square of argument
void outputSquare( int value ) 
{ 
   cout << value * value << ' '; 

} // end function outputSquare

// return cube of argument
int calculateCube( int value ) 
{ 
   return value * value * value; 

} // end function calculateCube

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 * (C) Copyright 1992-2003 by Deitel & Associates, Inc. and Prentice      *
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