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 }
 </lang>
+=={{header|C++}}==
+{{trans|C#}}
+<lang cpp>//#include <functional>
+#include <iostream>
+#include <vector>
+template <typename C, typename A>
+void merge2(const C& c1, const C& c2, const A& action) {
+    auto i1 = std::cbegin(c1);
+    auto i2 = std::cbegin(c2);
+    while (i1 != std::cend(c1) && i2 != std::cend(c2)) {
+        if (*i1 <= *i2) {
+            action(*i1);
+            i1 = std::next(i1);
+        } else {
+            action(*i2);
+            i2 = std::next(i2);
+        }
+    }
+    while (i1 != std::cend(c1)) {
+        action(*i1);
+        i1 = std::next(i1);
+    }
+    while (i2 != std::cend(c2)) {
+        action(*i2);
+        i2 = std::next(i2);
+    }
+}
+template <typename A, typename C>
+void mergeN(const A& action, std::initializer_list<C> all) {
+    using I = typename C::const_iterator;
+    using R = std::pair<I, I>;
+    std::vector<R> vit;
+    for (auto& c : all) {
+        auto p = std::make_pair(std::cbegin(c), std::cend(c));
+        vit.push_back(p);
+    }
+    bool done;
+    R* least;
+    do {
+        done = true;
+        auto it = vit.begin();
+        auto end = vit.end();
+        least = nullptr;
+        // search for the first non-empty range to use for comparison
+        while (it != end && it->first == it->second) {
+            it++;
+        }
+        if (it != end) {
+            least = &(*it);
+        }
+        while (it != end) {
+            // search for the next non-empty range to use for comaprison
+            while (it != end && it->first == it->second) {
+                it++;
+            }
+            if (least != nullptr && it != end
+                && it->first != it->second
+                && *(it->first) < *(least->first)) {
+                // found a smaller value
+                least = &(*it);
+            }
+            if (it != end) {
+                it++;
+            }
+        }
+        if (least != nullptr && least->first != least->second) {
+            done = false;
+            action(*(least->first));
+            least->first = std::next(least->first);
+        }
+    } while (!done);
+}
+void display(int num) {
+    std::cout << num << ' ';
+}
+int main() {
+    std::vector<int> v1{ 0, 3, 6 };
+    std::vector<int> v2{ 1, 4, 7 };
+    std::vector<int> v3{ 2, 5, 8 };
+    merge2(v2, v1, display);
+    std::cout << '\n';
+    mergeN(display, { v1 });
+    std::cout << '\n';
+    mergeN(display, { v3, v2, v1 });
+    std::cout << '\n';
+}</lang>
+{{out}}
+<pre>0 1 3 4 6 7
+3 6
+1 2 3 4 5 6 7 8</pre>
 =={{header|C#|C sharp}}==