CStdString str = "Hello World"; str.ToLower(); // str now contains "hello world"
CStdString str = "This Is A Test"; for (int i = 0; i < str.length(); i++) { str[i] = tolower(str[i]); } // str now contains "this is a test"In this example, each character in the CStdString object `str` is converted to lowercase using the C standard library function `tolower`. The package library for CStdString and its methods is the MFC (Microsoft Foundation Classes) library.