diff --git a/DIRECTORY.md b/DIRECTORY.md
index 9a2481213..048b95a41 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -245,7 +245,7 @@
   * [Reverse Binary Tree](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/operations_on_datastructures/reverse_binary_tree.cpp)
   * [Selectionsortlinkedlist](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/operations_on_datastructures/selectionsortlinkedlist.cpp)
   * [Trie Multiple Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/operations_on_datastructures/trie_multiple_search.cpp)
-  * [Union Of 2 Arrays](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/operations_on_datastructures/union_of_2_arrays.cpp)
+  * [Union Of Two Arrays](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/operations_on_datastructures/union_of_two_arrays.cpp)
 
 ## Others
   * [Buzz Number](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/others/buzz_number.cpp)
diff --git a/operations_on_datastructures/union_of_2_arrays.cpp b/operations_on_datastructures/union_of_2_arrays.cpp
deleted file mode 100644
index cdacf1d2e..000000000
--- a/operations_on_datastructures/union_of_2_arrays.cpp
+++ /dev/null
@@ -1,27 +0,0 @@
-#include <iostream>
-int main() {
-    int m, n, i = 0, j = 0;
-    cout << "Enter size of both arrays:";
-    cin >> m >> n;
-    int a[m];
-    int b[n];
-    cout << "Enter elements of array 1:";
-    for (i = 0; i < m; i++) cin >> a[i];
-    cout << "Enter elements of array 2:";
-    for (i = 0; i < n; i++) cin >> b[i];
-    i = 0;
-    j = 0;
-    while ((i < m) && (j < n)) {
-        if (a[i] < b[j])
-            cout << a[i++] << " ";
-        else if (a[i] > b[j])
-            cout << b[j++] << " ";
-        else {
-            cout << a[i++];
-            j++;
-        }
-    }
-    while (i < m) cout << a[i++] << " ";
-    while (j < n) cout << b[j++] << " ";
-    return 0;
-}
diff --git a/operations_on_datastructures/union_of_two_arrays.cpp b/operations_on_datastructures/union_of_two_arrays.cpp
new file mode 100644
index 000000000..45433379e
--- /dev/null
+++ b/operations_on_datastructures/union_of_two_arrays.cpp
@@ -0,0 +1,219 @@
+/**
+ * @file
+ * @brief Implementation for the [Union of two sorted
+ * Arrays](https://en.wikipedia.org/wiki/Union_(set_theory))
+ * algorithm.
+ * @details The Union of two arrays is the collection of all the unique elements
+ * in the first array, combined with all of the unique elements of a second
+ * array. This implementation uses ordered arrays, and an algorithm to correctly
+ * order them and return the result as a new array (vector).
+ * @author [Alvin](https://github.com/polarvoid)
+ */
+
+#include <algorithm>  /// for std::sort
+#include <cassert>    /// for assert
+#include <iostream>   /// for IO operations
+#include <vector>     /// for std::vector
+
+/**
+ * @namespace operations_on_datastructures
+ * @brief Operations on Data Structures
+ */
+namespace operations_on_datastructures {
+
+/**
+ * @brief Prints the values of a vector sequentially, ending with a newline
+ * character.
+ * @param array Reference to the array to be printed
+ * @returns void
+ */
+void print(const std::vector<int32_t> &array) {
+    for (int64_t i : array) {
+        std::cout << i << " ";  /// Print each value in the array
+    }
+    std::cout << "\n";  /// Print newline
+}
+
+/**
+ * @brief Gets the union of two sorted arrays, and returns them in a
+ * vector.
+ * @details An algorithm is used that compares the elements of the two vectors,
+ * appending the one that has a lower value, and incrementing the index for that
+ * array. If one of the arrays reaches its end, all the elements of the other
+ * are appended to the resultant vector.
+ * @param first A std::vector of sorted integer values
+ * @param second A std::vector of sorted integer values
+ * @returns A std::vector of the union of the two arrays, in ascending order
+ */
+std::vector<int32_t> get_union(const std::vector<int32_t> &first,
+                               const std::vector<int32_t> &second) {
+    std::vector<int32_t> res;         ///< Vector to hold the union
+    size_t f_index = 0;               ///< Index for the first array
+    size_t s_index = 0;               ///< Index for the second array
+    size_t f_length = first.size();   ///< Length of first array
+    size_t s_length = second.size();  ///< Length of second array
+    int32_t next = 0;  ///< Integer to store value of the next element
+
+    while (f_index < f_length && s_index < s_length) {
+        if (first[f_index] < second[s_index]) {
+            next = first[f_index];  ///< Append from first array
+            f_index++;              ///< Increment index of second array
+        } else if (first[f_index] > second[s_index]) {
+            next = second[s_index];  ///< Append from second array
+            s_index++;               ///< Increment index of second array
+        } else {
+            next = first[f_index];  ///< Element is the same in both
+            f_index++;              ///< Increment index of first array
+            s_index++;              ///< Increment index of second array too
+        }
+        if ((res.size() == 0) || (next != res.back())) {
+            res.push_back(next);  ///< Add the element if it is unique
+        }
+    }
+    while (f_index < f_length) {
+        next = first[f_index];  ///< Add remaining elements
+        if ((res.size() == 0) || (next != res.back())) {
+            res.push_back(next);  ///< Add the element if it is unique
+        }
+        f_index++;
+    }
+    while (s_index < s_length) {
+        next = second[s_index];  ///< Add remaining elements
+        if ((res.size() == 0) || (next != res.back())) {
+            res.push_back(next);  ///< Add the element if it is unique
+        }
+        s_index++;
+    }
+    return res;
+}
+
+}  // namespace operations_on_datastructures
+
+/**
+ * @namespace tests
+ * @brief Testcases to check Union of Two Arrays.
+ */
+namespace tests {
+using operations_on_datastructures::get_union;
+using operations_on_datastructures::print;
+/**
+ * @brief A Test to check an edge case (two empty arrays)
+ * @returns void
+ */
+void test1() {
+    std::cout << "TEST CASE 1\n";
+    std::cout << "Intialized a = {} b = {}\n";
+    std::cout << "Expected result: {}\n";
+    std::vector<int32_t> a = {};
+    std::vector<int32_t> b = {};
+    std::vector<int32_t> result = get_union(a, b);
+    assert(result == a);  ///< Check if result is empty
+    print(result);        ///< Should only print newline
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check an edge case (one empty array)
+ * @returns void
+ */
+void test2() {
+    std::cout << "TEST CASE 2\n";
+    std::cout << "Intialized a = {} b = {2, 3}\n";
+    std::cout << "Expected result: {2, 3}\n";
+    std::vector<int32_t> a = {};
+    std::vector<int32_t> b = {2, 3};
+    std::vector<int32_t> result = get_union(a, b);
+    assert(result == b);  ///< Check if result is equal to b
+    print(result);        ///< Should print 2 3
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check correct functionality with a simple test case
+ * @returns void
+ */
+void test3() {
+    std::cout << "TEST CASE 3\n";
+    std::cout << "Intialized a = {4, 6} b = {2, 3}\n";
+    std::cout << "Expected result: {2, 3, 4, 6}\n";
+    std::vector<int32_t> a = {4, 6};
+    std::vector<int32_t> b = {2, 3};
+    std::vector<int32_t> result = get_union(a, b);
+    std::vector<int32_t> expected = {2, 3, 4, 6};
+    assert(result == expected);  ///< Check if result is correct
+    print(result);               ///< Should print 2 3 4 6
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check correct functionality with duplicate values
+ * @returns void
+ */
+void test4() {
+    std::cout << "TEST CASE 4\n";
+    std::cout << "Intialized a = {4, 6, 6, 7} b = {2, 3, 4}\n";
+    std::cout << "Expected result: {2, 3, 4, 6, 7}\n";
+    std::vector<int32_t> a = {4, 6, 6, 7};
+    std::vector<int32_t> b = {2, 3, 4};
+    std::vector<int32_t> result = get_union(a, b);
+    std::vector<int32_t> expected = {2, 3, 4, 6, 7};
+    assert(result == expected);  ///< Check if result is correct
+    print(result);               ///< Should print 2 3 4 6 7
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check correct functionality with a harder test case
+ * @returns void
+ */
+void test5() {
+    std::cout << "TEST CASE 5\n";
+    std::cout << "Intialized a = {1, 4, 6, 7, 9} b = {2, 3, 5}\n";
+    std::cout << "Expected result: {1, 2, 3, 4, 5, 6, 7, 9}\n";
+    std::vector<int32_t> a = {1, 4, 6, 7, 9};
+    std::vector<int32_t> b = {2, 3, 5};
+    std::vector<int32_t> result = get_union(a, b);
+    std::vector<int32_t> expected = {1, 2, 3, 4, 5, 6, 7, 9};
+    assert(result == expected);  ///< Check if result is correct
+    print(result);               ///< Should print 1 2 3 4 5 6 7 9
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check correct functionality with an array sorted using
+ * std::sort
+ * @returns void
+ */
+void test6() {
+    std::cout << "TEST CASE 6\n";
+    std::cout << "Intialized a = {1, 3, 3, 2, 5, 9, 4, 3, 2} ";
+    std::cout << "b = {11, 3, 7, 8, 6}\n";
+    std::cout << "Expected result: {1, 2, 3, 4, 5, 6, 7, 8, 9, 11}\n";
+    std::vector<int32_t> a = {1, 3, 3, 2, 5, 9, 4, 3, 2};
+    std::vector<int32_t> b = {11, 3, 7, 8, 6};
+    std::sort(a.begin(), a.end());  ///< Sort vector a
+    std::sort(b.begin(), b.end());  ///< Sort vector b
+    std::vector<int32_t> result = get_union(a, b);
+    std::vector<int32_t> expected = {1, 2, 3, 4, 5, 6, 7, 8, 9, 11};
+    assert(result == expected);  ///< Check if result is correct
+    print(result);               ///< Should print 1 2 3 4 5 6 7 8 9 11
+    std::cout << "TEST PASSED!\n\n";
+}
+}  // namespace tests
+
+/**
+ * @brief Function to test the correctness of get_union() function
+ * @returns void
+ */
+static void test() {
+    tests::test1();
+    tests::test2();
+    tests::test3();
+    tests::test4();
+    tests::test5();
+    tests::test6();
+}
+
+/**
+ * @brief main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
+}