ACE_CString str1 = "Hello"; ACE_CString str2 = "World!"; ACE_CString str3 = str1 + " " + str2; size_t len1 = str1.length(); size_t len2 = str2.length(); size_t len3 = str3.length(); cout << "Length of str1: " << len1 << endl; cout << "Length of str2: " << len2 << endl; cout << "Length of str3: " << len3 << endl;In this example, we create three ACE_CString objects and concatenate them together to form a longer string. We then use the length() method to determine the length of each individual string and the concatenated string. The ACE library is a collection of packages that provide networking and communication features for C++ applications. It is open source and freely available for use in commercial and non-commercial projects.