Why is it allowed to pass R-Values by const reference but not by normal reference?

Question

as the title says why is it allowed to pass R-Values(literals) by constant reference but not normal reference

void display(const int& a)
{
cout <<         


        

Answer 1

For your final question:

how can a const reference keep pointing to an R-Value (anonymous variable)

Here is the answer. The C++ language says that a local const reference prolongs the lifetime of temporary values until the end of the containing scope, but saving you the cost of a copy-construction (i.e. if you were to use an local variable instead).