fig20_30.cpp

来自「这是C＋＋编程经典的书上实例的源代码。 （英文名是《C＋＋ how to pr」· C++ 代码 · 共 81 行

// Fig. 20.30: fig20_30.cpp
// Examples of mathematical algorithms in the Standard Library.
#include <iostream>

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

#include <algorithm>
#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 );
   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 );
   int result = std::count( v2.begin(), v2.end(), 8 );
   std::cout << "\nNumber of elements matching 8: " << result;
 
   result = std::count_if( v2.begin(), v2.end(), greater9 );
   cout << "\nNumber of elements greater than 9: " << result;

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

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

   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";
   std::for_each( v.begin(), v.end(), outputSquare );

   std::vector< int > cubes( SIZE );
   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;
}

bool greater9( int value ) { return value > 9; }

void outputSquare( int value ) { cout << value * value << ' '; }

int calculateCube( int value ) { return value * value * value; }

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