alg4.cpp

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#include <list>
#include <set>
#include <algorithm>
#include <iostream>
#include <iterator>
 
#include <examples.h>
 
typedef std::ostream_iterator<int, char, std::char_traits<char> >
ostrm_iter_type;
 
 
bool isEven (int n) {
    return 0 == (n % 2);
}
 
 
// Illustrate the use of the remove algorithm.
void remove_example ()
{
    std::cout << "Remove Algorithm examples" << std::endl;
 
    // Create a list of numbers.
    int data[] = { 1, 2, 4, 3, 1, 4, 2 };
    std::list<int, std::allocator<int> > aList;
 
    std::copy (data, data+7, std::inserter (aList, aList.begin ()));
    std::cout << "Original list: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    // Remove 2's, copy into a new list.
    std::list<int, std::allocator<int> > newList;
 
    std::remove_copy (aList.begin (), aList.end (),
                      std::back_inserter (newList), 2);
    std::cout << "After removing 2's: ";
    std::copy (newList.begin (), newList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    // Remove 2's in place.
    std::list<int, std::allocator<int> >::iterator 
        where = std::remove (aList.begin (), aList.end (), 2);
 
    std::cout << "List after removal, before erase: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    aList.erase (where, aList.end ());
    std::cout << "List after erase: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    // Remove all even values.
    where = std::remove_if (aList.begin (), aList.end (), isEven);
    aList.erase (where, aList.end ());
 
    std::cout << "List after removing even values: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
}
 
 
// Illustrate use of the unqiue algorithm.
void unique_example ()
{
    // First make a list of values.
    int data[] = { 1, 3, 3, 2, 2, 4 };
    std::list<int, std::allocator<int> > aList;
 
    std::copy (data, data+6, std::inserter (aList, aList.begin ()));
    std::cout << "Origianal List: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
 
    std::cout << std::endl;
 
    // Copy unique elements into a set.
    std::set<int, std::less<int>, std::allocator<int>  > aSet;
 
    std::unique_copy (aList.begin (), aList.end (),
                      std::inserter (aSet, aSet.begin ()));
 
    std::cout << "Set after unique_copy: ";
    std::copy (aSet.begin (), aSet.end (), ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    // Copy unique elements in place.
    std::list<int, std::allocator<int> >::iterator 
        where = std::unique (aList.begin (), aList.end ());
 
    std::cout << "List after calling unique: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
    // Remove trailing values.
    aList.erase (where, aList.end ());
 
    std::cout << "List after erase: ";
    std::copy (aList.begin (), aList.end (),
               ostrm_iter_type (std::cout, " "));
 
    std::cout << std::endl;
 
}
 
int main ()
{
    std::cout << "STL generic algorithms -- Removal Algorithms"
              << std::endl;
 
    remove_example ();
    unique_example ();
    
    std::cout << "End of removal algorithms sample program"
              << std::endl;
 
    return 0;
}