String concatenation

Question

Why it is possible to do

const string exclam = \"!\";
const string str = exclam + \"Hello\" + \" world\";

And not possible to do this:

Answer 1

In addition to the answers that explain the reason for your observations, I post here how to get rid of the problem (you might have figured this out already).

Replace

const string str = "Hello" + " world" + exclam;

with

const string str = string("Hello") + " world" + exclam;

so you make sure the first operand is a string and not a const char[].