why is reference initialization with 'operator ++' gives error

Question

#include<iostream.h> 
int main()
{
    int m = 2;
    int &x = m++;
    cout<<m;
    return 0; 
}

this code should gives OUTPUT: 3

but this code gives error: invalid initialization of non-const reference of type 'int&' from a temporary of type 'int'.

Answer 1

Post increment operator returns a temporary object with the value of m before increment. Non const lvalue references can't be bound to temporary objects. Thus, the compiler rightfully complains.