examples/manual/for_each.cpp

/**************************************************************************
 *
 * for_each.cpp - Example program for applying a function to each element 
 *                in a range.
 *
 * $Id: //stdlib/dev/examples/stdlib/manual/for_each.cpp#10 $
 *
 ***************************************************************************
 *
 * Copyright (c) 1994-2005 Quovadx,  Inc., acting through its  Rogue Wave
 * Software division. Licensed under the Apache License, Version 2.0 (the
 * "License");  you may  not use this file except  in compliance with the
 * License.    You    may   obtain   a   copy   of    the   License    at
 * http://www.apache.org/licenses/LICENSE-2.0.    Unless   required    by
 * applicable law  or agreed to  in writing,  software  distributed under
 * the License is distributed on an "AS IS" BASIS,  WITHOUT WARRANTIES OR
 * CONDITIONS OF  ANY KIND, either  express or implied.  See  the License
 * for the specific language governing permissions  and limitations under
 * the License.
 * 
 **************************************************************************/

#include <algorithm>    // for for_each
#include <functional>   // for less, unary_function
#include <iostream>     // for cout, endl
#include <set>          // for set

#include <examples.h>


// Function object that outputs its argument times x.
template <class Arg>
class out_times_x:  public std::unary_function<Arg, void>
{
    Arg multiplier;
public:
    out_times_x (const Arg &x) : multiplier (x) { }

    void operator() (const Arg &x) const {
        std::cout << x * multiplier << " " << std::endl;
    }
};


int main ()
{
    // Typedef for convenience.
    typedef std::set<int, std::less<int>, std::allocator<int> > sequence;
    
    sequence::value_type arr [] = { 1, 2, 3, 4, 5 };

    // Populate a sequence from arr.
    sequence s (arr, arr + sizeof arr / sizeof *arr);

    // Construct a function object.
    out_times_x<sequence::value_type> f2 (2);
  
    // Apply function object's operator() to each element.
    std::for_each (s.begin (), s.end (), f2);
  
    return 0;
}