The most efficient and secure way to use a `CString` object in called functions is to pass a `CString` object to the function. Despite the name, a `CString` object doesn't store a string internally as a C-style string that has a null terminator. Instead, a `CString` object keeps careful track of the number of characters it has. Having `CString` provide a `LPCTSTR` pointer to a null-terminated string is a small amount of work that can become significant if your code has to do it constantly. The result is temporary because any change to the `CString` contents invalidates old copies of the `LPCTSTR` pointer.

It does make sense in some cases to provide a C-style string. For example, there can be a situation where a called function is written in C and doesn't support objects. In this case, coerce the `CString` parameter to `LPCTSTR`, and the function will get a C-style null-terminated string. You can also go the other direction and create a `CString` object by using the `CString` constructor that accepts a C-style string parameter.