#includeIn the above example, the toLowerCase function is used to convert all uppercase characters in the string "HELLO WORLD" to lowercase. The output of the program would be "hello world". The toLowerCase function is part of the standard string library in cpp.#include int main() { std::string str = "HELLO WORLD"; // converting all uppercase characters to lowercase for(int i = 0; i < str.length(); i++) { str[i] = tolower(str[i]); } std::cout << str << std::endl; return 0; }