Add C++ unordered_set begin() documentation entry

content/cpp/concepts/unordered-set/terms/begin/begin.md

@@ -0,0 +1,79 @@
+---
+Title: '.begin()'
+Description: 'Returns an iterator pointing to the first element in the unordered_set.'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Iterators'
+  - 'Methods'
+  - 'Sets'
+CatalogContent:
+  - 'learn-c-plus-plus'
+  - 'paths/computer-science'
+---
+
+In C++, the **`.begin()`** [method](https://www.codecademy.com/resources/docs/cpp/methods) returns an iterator that points to the first element in the `unordered_set` container. Because `unordered_set` does not maintain sorted order, the element returned by `.begin()` is simply the first element in its internal bucket structure, not the "smallest" or "first" in any logical sense.
+
+## Syntax
+
+```pseudo
+mySet.begin(n);
+```
+
+**Parameters:**
+
+- `n` (Optional): The index of the bucket whose first element is to be accessed (must be in the range `0` to `mySet.bucket_count() - 1`).
+
+**Return value:**
+
+- `.begin()`: Returns an iterator that refers to the first element in the container. If the container is empty, the iterator equals `.end()`.
+- `.begin(n)`: Returns a local iterator that refers to the first element in bucket `n`. If the bucket is empty, the iterator equals `.end(n)`.
+
+## Example
+
+The following example demonstrates using `.begin()` to iterate through an `unordered_set`:
+
+```cpp
+#include <iostream>
+#include <unordered_set>
+
+int main() {
+  std::unordered_set<int> numbers = {10, 20, 30, 40, 50};
+
+  std::cout << "Elements in the unordered_set: ";
+  for (auto it = numbers.begin(); it != numbers.end(); ++it) {
+    std::cout << *it << " ";
+  }
+
+  return 0;
+}
+```
+
+This outputs the elements in the `unordered_set` (order may vary):
+
+```shell
+Elements in the unordered_set: 50 40 30 20 10
+```
+
+## Codebyte Example
+
+The following runnable example shows how to use `.begin()` with an `unordered_set`:
+
+```codebyte/cpp
+#include <iostream>
+#include <unordered_set>
+
+int main() {
+  std::unordered_set<std::string> fruits = {"apple", "banana", "orange"};
+
+  std::cout << "First fruit: " << *fruits.begin() << std::endl;
+
+  std::cout << "All fruits: ";
+  for (auto it = fruits.begin(); it != fruits.end(); ++it) {
+    std::cout << *it << " ";
+  }
+
+  return 0;
+}
+```