#includeIn the example code above, we create a std::wstring object named "str" and initialize it with the text "Hello, world!". We then extract a substring starting from index 0 and having a length of 5 characters, and store it in a new std::wstring object named "substr". We also create a reversed version of the original string by using reverse iterators, and store it in the std::wstring object named "reversed_str". We then access a single character from the original string using the .at() method, and store it in a wchar_t variable named "ch". Finally, we print the original string to the standard output using std::wcout. Overall, std::wstring is a useful class for working with Unicode strings in C++. It supports a wide range of operations, such as concatenation, comparison, and conversion between different formats.int main() { std::wstring str = L"Hello, world!"; // creating a wide string with an "L" prefix before the regular string literal std::wstring substr = str.substr(0, 5); // extracting a substring from the original string std::wstring reversed_str(str.rbegin(), str.rend()); // reversing the string using reverse iterators wchar_t ch = str.at(1); // accessing the character at index 1 std::wcout << str << '\n'; // printing the wide string to standard output return 0; }