constant references with typedef and templates in c++

Question

I heard the temporary objects can only be assigned to constant references.

But this code gives error

#include     
template

        

Answer 1

It's a very common mistake for English speaking people, because of the way the English grammar works.

I consider it extremely unfortunate that the C++ syntax would allow both:

const int // immutable int
int const // immutable int

to have the same meaning.

It doesn't make it easier, really, and isn't composable since:

const int* // mutable pointer to immutable int
int* const // immutable pointer to mutable int

certainly do NOT have the same meaning.

And this, unfortunately for you, what kicks in here, as @GMan explains.

If you wish to avoid this kind of error in the future, take the habit of qualifying your types (const and volatile) on their right, then you'll be able to treat a typedef as simple text replacement.