What is operator promotion?

If an operation is specified with operands of two different types, they are converted to the smallest type that can hold both values. The result has the same type as the two operands wind up having. To interpret the rules, read the following table from the top down, and stop at the first rule that applies.

The following example code illustrates some cases of operator

Can a variable be both const and volatile?

Yes. The const modifier means that this code cannot change the value of the variable, but that does not mean that the value cannot be changed by means outside this code. For instance, in the above example, the timer structure was accessed through a volatile const pointer. The function itself did not change the value of the timer, so it

When should the volatile modifier be used?

The volatile modifier is a directive to the compiler’s optimizer that operations involving this variable should not be optimized in certain ways. There are two special cases in which use of the volatile modifier is desirable. The first case involves memory-mapped hardware (a device such as a graphics adaptor that appears to the computer’s hardware as if it were part of the computer’s memory), and the second involves shared memory (memory used by two or more programs running simultaneously).

Most computers have a set of registers that can be accessed faster than the computer’s main memory. A good compiler will perform a