Advantages of using user-defined literal for strings instead of string literal

Question

The strings topic in the SO Documentation used to say, in the Remarks section:

Since C++14, instead of using \"foo\", it is recommended t

Answer 1

The advice to use "blah"s has nothing to do with efficiency and all to do with correctness for novice code.

C++ novices who don't have a background in C, tend to assume that "blah" results in an object of some reasonable string type. For example, so that one can write things like "blah" + 42, which works in many script languages. With "blah" + 42 in C++, however, one just incurs Undefined Behavior, addressing beyond the end of the character array.

But if that string literal is written as "blah"s then one instead gets a compilation error, which is much preferable.