CharArray
=========

.. cpp:class:: numpy::CharArray

   numpy C++ class.

Example
-------

.. code-block:: cpp

   #include <numpy/np_ndarray.h>
   using namespace numpy;

   // Use CharArray
   CharArray obj;
   // ... operations ...

Constructors
------------

.. list-table::
   :widths: 55 25 20
   :header-rows: 1

   * - Signature
     - Location
     - Example
   * - ``CharArray(const std::vector<size_t>&shape)``
     - NP_CHARARRAY.H:54
     - 
   * - ``CharArray(const std::vector<size_t>&shape, const std::string &fill_value)``
     - NP_CHARARRAY.H:57
     - 
   * - ``CharArray(const NDArray<str\_<N>>&array)``
     - NP_CHARARRAY.H:60
     - 
   * - ``CharArray(const CharArray &other)``
     - NP_CHARARRAY.H:64
     - 

Operators
---------

.. list-table::
   :widths: 40 25 15 20
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``CharArray & operator=(const CharArray &other)``
     - CharArray &
     - NP_CHARARRAY.H:67
     - 
   * - ``std::string operator[](const std::vector<size_t>&indices)``
     - std::string
     - NP_CHARARRAY.H:84
     - 
   * - ``std::string operator[](size_tindex)``
     - std::string
     - NP_CHARARRAY.H:93
     - 
   * - ``NDArray<bool> operator==(const CharArray &other)``
     - NDArray<bool>
     - NP_CHARARRAY.H:391
     - 
   * - ``NDArray<bool> operator!=(const CharArray &other)``
     - NDArray<bool>
     - NP_CHARARRAY.H:402
     - 
   * - ``CharArray operator+(const CharArray &other)``
     - CharArray
     - NP_CHARARRAY.H:414
     - 
   * - ``CharArray operator+(const std::string &scalar)``
     - CharArray
     - NP_CHARARRAY.H:418
     - 
   * - ``CharArray operator\*(size_trepeats)``
     - CharArray
     - NP_CHARARRAY.H:422
     - 

Array Creation
--------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``std::string trimmed(const str\_<N>&s)``
     - std::string
     - NP_CHARARRAY.H:40
     - 

Math Operations
---------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``CharArray add(const CharArray &other)``
     - CharArray
     - NP_CHARARRAY.H:104
     - :ref:`View <example-chararray-add-0>`
   * - ``CharArray add(const std::string &scalar)``
     - CharArray
     - NP_CHARARRAY.H:108
     - :ref:`View <example-chararray-add-1>`
   * - ``CharArray multiply(size_trepeats)``
     - CharArray
     - NP_CHARARRAY.H:118
     - :ref:`View <example-chararray-multiply-2>`

Other Methods
-------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``const NDArray<str\_<N>>& array()``
     - const NDArray<str\_<N>>&
     - NP_CHARARRAY.H:75
     - :ref:`View <example-chararray-array-3>`
   * - ``NDArray<str\_<N>>& array()``
     - NDArray<str\_<N>>&
     - NP_CHARARRAY.H:76
     - :ref:`View <example-chararray-array-4>`
   * - ``CharArray capitalize()``
     - CharArray
     - NP_CHARARRAY.H:123
     - :ref:`View <example-chararray-capitalize-5>`
   * - ``CharArray lower()``
     - CharArray
     - NP_CHARARRAY.H:150
     - :ref:`View <example-chararray-lower-6>`
   * - ``CharArray lstrip(const std::string &chars = " 	\\n\\r\\f\\v")``
     - CharArray
     - NP_CHARARRAY.H:219
     - :ref:`View <example-chararray-lstrip-7>`
   * - ``size_t ndim()``
     - size_t
     - NP_CHARARRAY.H:81
     - :ref:`View <example-chararray-ndim-8>`
   * - ``str\_<N> padded(const std::string &s)``
     - str\_<N>
     - NP_CHARARRAY.H:48
     - 
   * - ``void print()``
     - void
     - NP_CHARARRAY.H:432
     - :ref:`View <example-chararray-print-9>`
   * - ``CharArray rstrip(const std::string &chars = " 	\\n\\r\\f\\v")``
     - CharArray
     - NP_CHARARRAY.H:235
     - :ref:`View <example-chararray-rstrip-10>`
   * - ``void set(const std::vector<size_t>&indices, const std::string &value)``
     - void
     - NP_CHARARRAY.H:88
     - :ref:`View <example-chararray-set-11>`
   * - ``void set(size_tindex, const std::string &value)``
     - void
     - NP_CHARARRAY.H:97
     - :ref:`View <example-chararray-set-12>`
   * - ``const std::vector<size_t>& shape()``
     - const std::vector<size_t>&
     - NP_CHARARRAY.H:79
     - :ref:`View <example-chararray-shape-13>`
   * - ``size_t size()``
     - size_t
     - NP_CHARARRAY.H:80
     - :ref:`View <example-chararray-size-14>`
   * - ``CharArray strip(const std::string &chars = " 	\\n\\r\\f\\v")``
     - CharArray
     - NP_CHARARRAY.H:198
     - :ref:`View <example-chararray-strip-15>`
   * - ``CharArray swapcase()``
     - CharArray
     - NP_CHARARRAY.H:180
     - :ref:`View <example-chararray-swapcase-16>`
   * - ``CharArray title()``
     - CharArray
     - NP_CHARARRAY.H:161
     - :ref:`View <example-chararray-title-17>`
   * - ``std::string toString()``
     - std::string
     - NP_CHARARRAY.H:427
     - :ref:`View <example-chararray-tostring-18>`
   * - ``CharArray upper()``
     - CharArray
     - NP_CHARARRAY.H:139
     - :ref:`View <example-chararray-upper-19>`


Code Examples
-------------

The following examples are extracted from the test suite.

.. _example-chararray-add-0:

.. dropdown:: add (np_test_1_all.cpp:6410)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6400
      :emphasize-lines: 11

      void testCharArrayStringOperationsCharArray() {
          std::cout << "========= testStringOperations =======================";
      
          // Test string concatenation
          std::vector<std::string> words1 = {"Hello", "Good", "Nice"};
          std::vector<std::string> words2 = {" World", " Day", " Work"};
      
          auto arr1 = array<32>(words1);
          auto arr2 = array<32>(words2);
      
          auto result = add(arr1, arr2);
          // std::cout << "String concatenation (add):" << std::endl;
          for (size_t i = 0; i < result.size(); ++i) {
              // std::cout << "'" << arr1[i] << "' + '" << arr2[i] << "' = '" << result[i] << "'";
          }
      
          // Test scalar addition
          auto scalar_result = add(arr1, "!");
          // std::cout << "Scalar concatenation:" << std::endl;
          for (size_t i = 0; i < scalar_result.size(); ++i) {
              // std::cout << "'" << arr1[i] << "' + '!' = '" << scalar_result[i] << "'";

.. _example-chararray-add-1:

.. dropdown:: add (np_test_1_all.cpp:6410)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6400
      :emphasize-lines: 11

      void testCharArrayStringOperationsCharArray() {
          std::cout << "========= testStringOperations =======================";
      
          // Test string concatenation
          std::vector<std::string> words1 = {"Hello", "Good", "Nice"};
          std::vector<std::string> words2 = {" World", " Day", " Work"};
      
          auto arr1 = array<32>(words1);
          auto arr2 = array<32>(words2);
      
          auto result = add(arr1, arr2);
          // std::cout << "String concatenation (add):" << std::endl;
          for (size_t i = 0; i < result.size(); ++i) {
              // std::cout << "'" << arr1[i] << "' + '" << arr2[i] << "' = '" << result[i] << "'";
          }
      
          // Test scalar addition
          auto scalar_result = add(arr1, "!");
          // std::cout << "Scalar concatenation:" << std::endl;
          for (size_t i = 0; i < scalar_result.size(); ++i) {
              // std::cout << "'" << arr1[i] << "' + '!' = '" << scalar_result[i] << "'";

.. _example-chararray-multiply-2:

.. dropdown:: multiply (np_test_1_all.cpp:6426)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6416
      :emphasize-lines: 11

          // Test scalar addition
          auto scalar_result = add(arr1, "!");
          // std::cout << "Scalar concatenation:" << std::endl;
          for (size_t i = 0; i < scalar_result.size(); ++i) {
              // std::cout << "'" << arr1[i] << "' + '!' = '" << scalar_result[i] << "'";
          }
      
          // Test string multiplication
          std::vector<std::string> patterns = {"Ha", "Ho", "Hi"};
          auto pattern_arr = array<32>(patterns);
          auto repeated = multiply(pattern_arr, 3);
          // std::cout << "String multiplication:" << std::endl;
          for (size_t i = 0; i < repeated.size(); ++i) {
              // std::cout << "'" << pattern_arr[i] << "' * 3 = '" << repeated[i] << "'";
          }
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testCaseConversionsCharArray() {
          std::cout << "========= testCaseConversions =======================";

.. _example-chararray-array-3:

.. dropdown:: array (np_test_1_all.cpp:243)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 233
      :emphasize-lines: 11

          // std::cout << "Min: " << array.minArray() << std::endl;
          // std::cout << "Max: " << array.maxArray() << std::endl;
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testReshapeAndFlatten() {
          std::cout << "========= testReshapeAndFlatten =======================";
      
          auto range_array = NDArray<int32>::createRange(0, 12, 1);
          // std::cout << "Range array (0-11):" << std::endl;
          //range_array.printArray();
      
          auto reshaped = range_array.reshapeArray({3, 4});
          // std::cout << "Reshaped to 3x4:";
          //reshaped.printArray();
      
          auto flattened = reshaped.flattenArray();
          // std::cout << "Flattened:" << std::endl;
          //flattened.printArray();
      

.. _example-chararray-array-4:

.. dropdown:: array (np_test_1_all.cpp:243)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 233
      :emphasize-lines: 11

          // std::cout << "Min: " << array.minArray() << std::endl;
          // std::cout << "Max: " << array.maxArray() << std::endl;
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testReshapeAndFlatten() {
          std::cout << "========= testReshapeAndFlatten =======================";
      
          auto range_array = NDArray<int32>::createRange(0, 12, 1);
          // std::cout << "Range array (0-11):" << std::endl;
          //range_array.printArray();
      
          auto reshaped = range_array.reshapeArray({3, 4});
          // std::cout << "Reshaped to 3x4:";
          //reshaped.printArray();
      
          auto flattened = reshaped.flattenArray();
          // std::cout << "Flattened:" << std::endl;
          //flattened.printArray();
      

.. _example-chararray-capitalize-5:

.. dropdown:: capitalize (np_test_1_all.cpp:6461)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6451
      :emphasize-lines: 11

          }
      
          // Test lower case
          auto lower_result = lower(arr);
          // std::cout << "Lower case:" << std::endl;
          for (size_t i = 0; i < lower_result.size(); ++i) {
              // std::cout << "  '" << lower_result[i] << "'";
          }
      
          // Test capitalize
          auto cap_result = capitalize(arr);
          // std::cout << "Capitalize:" << std::endl;
          for (size_t i = 0; i < cap_result.size(); ++i) {
              // std::cout << "  '" << cap_result[i] << "'";
          }
      
          // Test title
          auto title_result = title(arr);
          // std::cout << "Title case:" << std::endl;
          for (size_t i = 0; i < title_result.size(); ++i) {
              // std::cout << "  '" << title_result[i] << "'";

.. _example-chararray-lower-6:

.. dropdown:: lower (np_test_1_all.cpp:6454)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6444
      :emphasize-lines: 11

          }
      
          // Test upper case
          auto upper_result = upper(arr);
          // std::cout << "Upper case:" << std::endl;
          for (size_t i = 0; i < upper_result.size(); ++i) {
              // std::cout << "  '" << upper_result[i] << "'";
          }
      
          // Test lower case
          auto lower_result = lower(arr);
          // std::cout << "Lower case:" << std::endl;
          for (size_t i = 0; i < lower_result.size(); ++i) {
              // std::cout << "  '" << lower_result[i] << "'";
          }
      
          // Test capitalize
          auto cap_result = capitalize(arr);
          // std::cout << "Capitalize:" << std::endl;
          for (size_t i = 0; i < cap_result.size(); ++i) {
              // std::cout << "  '" << cap_result[i] << "'";

.. _example-chararray-lstrip-7:

.. dropdown:: lstrip (np_test_1_all.cpp:6641)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6631
      :emphasize-lines: 11

          }
      
          // Test strip
          auto stripped = strip(arr);
          // std::cout << "After strip():" << std::endl;
          for (size_t i = 0; i < stripped.size(); ++i) {
              // std::cout << "'" << stripped[i] << "'";
          }
      
          // Test lstrip
          auto left_stripped = lstrip(arr);
          // std::cout << "After lstrip():" << std::endl;
          for (size_t i = 0; i < left_stripped.size(); ++i) {
              // std::cout << "'" << left_stripped[i] << "'";
          }
      
          // Test rstrip
          auto right_stripped = rstrip(arr);
          // std::cout << "After rstrip():" << std::endl;
          for (size_t i = 0; i < right_stripped.size(); ++i) {
              // std::cout << "'" << right_stripped[i] << "'";

.. _example-chararray-ndim-8:

.. dropdown:: ndim (np_test_2_all.cpp:3526)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 3516
      :emphasize-lines: 11

          void testArrayInfo() {
            std::cout << "Testing array information functions...\n";
      
            // Test basic info functions
            auto arr = createFloat64Array({ 2, 3, 4 });
            for (size_t i = 0; i < arr.getSize(); ++i) {
              arr.setElementAt({ i / 12, (i / 4) % 3, i % 4 }, static_cast<double>(i));
            }
      
            // Test ndim
            if (!(ndim(arr) == 3)) {
                std::string description = std::string("testArrayInfo():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(ndim(arr) == 3)";
                std::cout << std::string("[FAIL] ") + description << std::endl;
                throw std::runtime_error(description);
            }
      
            // Test size
            if (!(size(arr) == 24)) {
                std::string description = std::string("testArrayInfo():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(size(arr) == 24)";
                std::cout << std::string("[FAIL] ") + description << std::endl;
                throw std::runtime_error(description);

.. _example-chararray-print-9:

.. dropdown:: print (np_test_1_all.cpp:6395)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6385
      :emphasize-lines: 11

          std::vector<std::string> strings = {"Alice", "Bob", "Charlie"};
          auto arr2 = array<32>(strings);
          // std::cout << "Created from strings vector:" << std::endl;
          for (size_t i = 0; i < arr2.size(); ++i) {
              // std::cout << "arr2[" << i << "] = '" << arr2[i] << "'";
          }
      
          // Test 2D array creation
          chararray16 arr_2d({2, 3}, "test");
          // std::cout << "Created 2D chararray16 with shape {2, 3}:";
          // arr_2d.print();
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testCharArrayStringOperationsCharArray() {
          std::cout << "========= testStringOperations =======================";
      
          // Test string concatenation
          std::vector<std::string> words1 = {"Hello", "Good", "Nice"};
          std::vector<std::string> words2 = {" World", " Day", " Work"};

.. _example-chararray-rstrip-10:

.. dropdown:: rstrip (np_test_1_all.cpp:6648)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6638
      :emphasize-lines: 11

          }
      
          // Test lstrip
          auto left_stripped = lstrip(arr);
          // std::cout << "After lstrip():" << std::endl;
          for (size_t i = 0; i < left_stripped.size(); ++i) {
              // std::cout << "'" << left_stripped[i] << "'";
          }
      
          // Test rstrip
          auto right_stripped = rstrip(arr);
          // std::cout << "After rstrip():" << std::endl;
          for (size_t i = 0; i < right_stripped.size(); ++i) {
              // std::cout << "'" << right_stripped[i] << "'";
          }
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testStringComparisonCharArray() {
          std::cout << "========= testStringComparison =======================";

.. _example-chararray-set-11:

.. dropdown:: set (np_test_1_all.cpp:6747)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6737
      :emphasize-lines: 11

          std::cout << "========= testArrayPrinting =======================";
      
          // Test 1D array printing
          std::vector<std::string> words = {"Hello", "World", "Test"};
          auto arr_1d = array<16>(words);
          // std::cout << "1D CharArray:" << std::endl;
          // arr_1d.print();
      
          // Test 2D array printing
          chararray16 arr_2d({2, 2}, "test");
          arr_2d.set({0, 0}, "A");
          arr_2d.set({0, 1}, "B");
          arr_2d.set({1, 0}, "C");
          arr_2d.set({1, 1}, "D");
      
          // std::cout << "2D CharArray:" << std::endl;
          // arr_2d.print();
      
          std::cout << " -> tests passed" << std::endl;
      }
      

.. _example-chararray-set-12:

.. dropdown:: set (np_test_1_all.cpp:6747)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6737
      :emphasize-lines: 11

          std::cout << "========= testArrayPrinting =======================";
      
          // Test 1D array printing
          std::vector<std::string> words = {"Hello", "World", "Test"};
          auto arr_1d = array<16>(words);
          // std::cout << "1D CharArray:" << std::endl;
          // arr_1d.print();
      
          // Test 2D array printing
          chararray16 arr_2d({2, 2}, "test");
          arr_2d.set({0, 0}, "A");
          arr_2d.set({0, 1}, "B");
          arr_2d.set({1, 0}, "C");
          arr_2d.set({1, 1}, "D");
      
          // std::cout << "2D CharArray:" << std::endl;
          // arr_2d.print();
      
          std::cout << " -> tests passed" << std::endl;
      }
      

.. _example-chararray-shape-13:

.. dropdown:: shape (np_test_1_all.cpp:3751)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 3741
      :emphasize-lines: 11

          }
      
          for (size_t j = 0; j < 3; ++j) {
              arr3.setElementAt({0, j}, static_cast<double>((j + 1) * 100));  // [100, 200, 300]
          }
      
          // Broadcast all arrays together
          std::vector<NDArray<double>> arrays = {arr1, arr2, arr3};
          auto broadcasted = broadcast_arrays(arrays);
      
          // All should have shape (2, 3)
          for (const auto& arr : broadcasted) {
              if (!((arr.getShape() == std::vector<size_t>{2, 3}))) {
                  std::string description = std::string("test_broadcast_arrays():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !((arr.getShape() == std::vector<size_t>{2, 3}))";
                  std::cout << std::string("[FAIL] ") + description << std::endl;
                  throw std::runtime_error(description);
              }
          }
      
          // Check values
          if (!(broadcasted[0].getElementAt({0, 1}) == 2.0)) {

.. _example-chararray-size-14:

.. dropdown:: size (np_test_1_all.cpp:47)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 37
      :emphasize-lines: 11

      
      using namespace numpy;
      using namespace numpy::benchmark;
      using namespace numpy::char_;
      
      // Helper functions for array comparison tests
      namespace {
          const double TOLERANCE = 1e-10;
      
          bool allTrue(const NDArray<bool>& arr) {
              std::vector<size_t> indices(arr.getShape().size(), 0);
              do {
                  if (!arr.getElementAt(indices)) {
                      return false;
                  }
              } while (incrementIndices(indices, arr.getShape()));
              return true;
          }
      
          bool allFalse(const NDArray<bool>& arr) {
              std::vector<size_t> indices(arr.getShape().size(), 0);

.. _example-chararray-strip-15:

.. dropdown:: strip (np_test_1_all.cpp:6634)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6624
      :emphasize-lines: 11

      
          std::vector<std::string> padded = {"  hello  ", "\t\tworld\t\t", "   spaces   "};
          auto arr = array<32>(padded);
      
          // std::cout << "Original padded strings:" << std::endl;
          for (size_t i = 0; i < arr.size(); ++i) {
              // std::cout << "'" << arr[i] << "'";
          }
      
          // Test strip
          auto stripped = strip(arr);
          // std::cout << "After strip():" << std::endl;
          for (size_t i = 0; i < stripped.size(); ++i) {
              // std::cout << "'" << stripped[i] << "'";
          }
      
          // Test lstrip
          auto left_stripped = lstrip(arr);
          // std::cout << "After lstrip():" << std::endl;
          for (size_t i = 0; i < left_stripped.size(); ++i) {
              // std::cout << "'" << left_stripped[i] << "'";

.. _example-chararray-swapcase-16:

.. dropdown:: swapcase (np_test_5_all.cpp:1434)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 1424
      :emphasize-lines: 11

            }
      
            std::cout << " -> tests passed" << std::endl;
          }
      
          void np_test_string_swapcase() {
            std::cout << "========= swapcase formatting =======================";
      
            std::vector<std::string> strings = { "Hello World", "TEST", "test" };
            auto arr = numpy::char_::array<32>(strings);
            auto result = numpy::char_::swapcase(arr);
      
            bool passed = (result.size() == arr.size());
      
            if (!passed) {
              std::cout << "  [FAIL] : in np_test_string_swapcase() : size mismatch";
              throw std::runtime_error("np_test_string_swapcase failed");
            }
      
            std::cout << " -> tests passed" << std::endl;
          }

.. _example-chararray-title-17:

.. dropdown:: title (np_test_1_all.cpp:6468)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6458
      :emphasize-lines: 11

          }
      
          // Test capitalize
          auto cap_result = capitalize(arr);
          // std::cout << "Capitalize:" << std::endl;
          for (size_t i = 0; i < cap_result.size(); ++i) {
              // std::cout << "  '" << cap_result[i] << "'";
          }
      
          // Test title
          auto title_result = title(arr);
          // std::cout << "Title case:" << std::endl;
          for (size_t i = 0; i < title_result.size(); ++i) {
              // std::cout << "  '" << title_result[i] << "'";
          }
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testStringTestingCharArray() {
          std::cout << "========= testStringTesting =======================";

.. _example-chararray-tostring-18:

.. dropdown:: toString (np_test_1_all.cpp:6826)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6816
      :emphasize-lines: 11

      void testDatetime64CreationDateTime() {
          std::cout << "========= testDatetime64CreationDateTime =======================";
      
          // Test default constructor
          datetime64 default_dt;
          if (!(default_dt.isNaT())) {
              std::string description = std::string("testDatetime64CreationDateTime():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(default_dt.isNaT())";
              std::cout << std::string("[FAIL] ") + description << std::endl;
              throw std::runtime_error(description);
          }
          // std::cout << "Default datetime64 is NaT: " << default_dt.toString() << std::endl;
      
          // Test value constructor
          datetime64 epoch_day(0, DateTimeUnit::Day);
          // std::cout << "Epoch day: " << epoch_day.toString() << std::endl;
      
          // Test string constructor
          datetime64 date_from_string("2024-01-15");
          // std::cout << "Date from string '2024-01-15': " << date_from_string.toString() << std::endl;
      
          datetime64 datetime_from_string("2024-01-15T10:30:45");

.. _example-chararray-upper-19:

.. dropdown:: upper (np_test_1_all.cpp:6447)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6437
      :emphasize-lines: 11

      
          std::vector<std::string> mixed_case = {"hello world", "GOOD DAY", "Mixed Case"};
          auto arr = array<32>(mixed_case);
      
          // std::cout << "Original strings:" << std::endl;
          for (size_t i = 0; i < arr.size(); ++i) {
              // std::cout << "  '" << arr[i] << "'";
          }
      
          // Test upper case
          auto upper_result = upper(arr);
          // std::cout << "Upper case:" << std::endl;
          for (size_t i = 0; i < upper_result.size(); ++i) {
              // std::cout << "  '" << upper_result[i] << "'";
          }
      
          // Test lower case
          auto lower_result = lower(arr);
          // std::cout << "Lower case:" << std::endl;
          for (size_t i = 0; i < lower_result.size(); ++i) {
              // std::cout << "  '" << lower_result[i] << "'";