#includeThis example creates an ACE_CString object containing the string "Hello world!". It then calls the find method with the argument "world" and stores the result in the variable index. If the substring is found, the index is printed to the console using the ACE_DEBUG macro. Otherwise, a message indicating that the substring was not found is printed. The ACE_CString class is part of the ACE library, which is a collection of C++ classes for building networked applications. The library provides a framework for developing high-performance, scalable, and portable applications that can run on a variety of platforms.#include int main() { ACE_CString str = "Hello world!"; int index = str.find("world"); if (index != -1) { ACE_DEBUG((LM_DEBUG, "Found 'world' at index %d\n", index)); } else { ACE_DEBUG((LM_DEBUG, "'world' not found\n")); } return 0; }