The attitude that programmers should not have to pay for features
that they do not use permeates the [C++] language.  Another example
will further illustrate this influence.  Imagine that an integer
variable holding a negative number is right-shifted by one location.
What bit value should be moved into the topmost position?  If we
look at the machine level, architectural designers are divided on
this issue.  On some machines, a right shift will move a zero into
the most significant bit position, while on other machines the sign
bit (which, in the case of a negative number, will be 1) is extended.
Either case can be simulated by the other, using software, by means
of a combination of tests and masks.

-- p. 4, "C++ for Java Programmers", Timothy Budd (Addison-Wesley, 1999)