std::wstring str1 = L"Hello World!"; size_t pos = str1.find_last_of(L"ol");
std::wstring str2 = L"The quick brown fox jumps over the lazy dog."; size_t pos = str2.find_last_of(L"aeiou");In this example, the `find_last_of` function searches for the last occurrence of any vowel in the given string. The returned position is the index of the character 'o' in the string, which is 35. This function is included in the C++ Standard Library and does not require any additional packages.