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extern/stdcxx/4.2.1/examples/tutorial/alg6.cpp

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+/**************************************************************************
+ *
+ * alg6.cpp - STL generic algorithms that produce new sequences.
+ *
+ * $Id: alg6.cpp 550991 2007-06-26 23:58:07Z sebor $
+ *
+ ***************************************************************************
+ *
+ * Licensed to the Apache Software  Foundation (ASF) under one or more
+ * contributor  license agreements.  See  the NOTICE  file distributed
+ * with  this  work  for  additional information  regarding  copyright
+ * ownership.   The ASF  licenses this  file to  you 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.
+ *
+ * Copyright 1994-2006 Rogue Wave Software.
+ * 
+ **************************************************************************/
+
+#include <vector>
+#include <list>
+#include <functional>
+#include <algorithm>
+#include <numeric>
+#include <iostream>
+#include <iterator>
+#include <functional>
+
+#include <examples.h>
+
+typedef std::ostream_iterator<int, char, std::char_traits<char> > ostrm_iter_type;
+
+
+int square (int n) {
+    return n * n;
+}
+
+
+class iotaGen {
+public:
+    iotaGen (int iv) : current (iv)
+        { }
+    int operator () () {
+        return current++;
+    }
+private:
+    int current;
+};
+
+
+// Illustrate the use of the transform algorithm.
+void transform_example () {
+
+    // Generate a std::list of values from 1 to 6.
+    std::list<int, std::allocator<int> > aList;
+
+    std::generate_n (std::inserter (aList, aList.begin ()), 6, iotaGen (1));
+    std::cout << "Original list: ";
+    std::copy (aList.begin (), aList.end (), ostrm_iter_type (std::cout, " "));
+
+    std::cout << std::endl;
+
+    // Transform elements by squaring, copy into std::vector.
+    std::vector<int, std::allocator<int> > aVec (6);
+
+    std::transform (aList.begin (), aList.end (), aVec.begin (), square);
+    std::cout << "After squaring: ";
+    std::copy (aVec.begin (), aVec.end (), ostrm_iter_type (std::cout, " "));
+
+    std::cout << std::endl;
+
+    // Transform std::vector again, in place, yielding 4th powers.
+    std::transform (aVec.begin (), aVec.end (), aVec.begin (), square);
+    std::cout << "After squaring again: ";
+    std::copy (aVec.begin (), aVec.end (),ostrm_iter_type (std::cout, " "));
+
+    std::cout << std::endl;
+
+    // Transform in parallel, yielding cubes.
+    std::vector<int, std::allocator<int> > cubes (6);
+
+    std::transform (aVec.begin (), aVec.end (), aList.begin (), cubes.begin (),
+                   std::divides<int> ());
+    std::cout << "After division: ";
+    std::copy (cubes.begin (), cubes.end (), ostrm_iter_type (std::cout, " "));
+
+    std::cout << std::endl;
+}
+
+
+// Illustrate the use of the partial sum algorithm.
+void partial_sum_example () {
+
+    // Generate values 1 to 5.
+    std::vector<int, std::allocator<int> > aVec (5);
+    std::generate (aVec.begin (), aVec.end (), iotaGen (1));
+
+    // Output partial sums.
+    std::cout << "Partial sums examples" << std::endl;
+    std::cout << "Partial sums : ";
+    std::partial_sum (aVec.begin (), aVec.end (),
+                 ostrm_iter_type (std::cout, " "));
+
+    std::cout << std::endl;
+
+    // Output partial products.
+    std::cout << "Partial products: ";
+    std::partial_sum (aVec.begin (), aVec.end (),
+                 ostrm_iter_type (std::cout, " "), std::multiplies<int> () );
+
+    std::cout << std::endl;
+}
+
+
+// Illustrate the use of the adjacent difference algorithm.
+void adjacent_difference_example () {
+
+    // Generate values 1 to 5.
+    std::vector<int, std::allocator<int> > aVec (5);
+    std::generate (aVec.begin (), aVec.end (), iotaGen (1));
+
+    // Output partial sums.
+    std::cout << "Adjacent Differences examples" << std::endl;
+    std::cout << "Adjacent Differences : ";
+    std::adjacent_difference
+        (aVec.begin (), aVec.end (), ostrm_iter_type (std::cout, " "));
+    std::cout << std::endl;
+
+    // Output partial products.
+    std::cout << "Adjacent sums: ";
+    std::adjacent_difference (aVec.begin (), aVec.end (),
+                              ostrm_iter_type (std::cout, " "),
+                              std::plus<int> ());
+
+    std::cout << std::endl;
+}
+
+
+int main () {
+
+    std::cout << "STL generic algorithms -- that transform sequences"
+              << std::endl;
+
+    transform_example ();
+    partial_sum_example ();
+    adjacent_difference_example ();
+
+    std::cout << "End generic transform algorithms example" << std::endl;
+
+    return 0;
+}
+
+
+
+
+
+
+