Representing Boolean true/false

A Boolean value is one that evaluates to true or false. On some systems, YES and yes are equivalent to true, while NO and no are equivalent to false. For instance, Is today Wednesday? evaluates to true only 1 out of 7 days. On the other 6 days, it evaluates to false.

Before C99, there was no explicit type for a Boolean. A value of any type that is 0 (exactly 0) is considered as also evaluating to a Boolean false. Any value other than exactly 0 (a bit pattern of only 0s) will evaluate to a Boolean value of true. Real numbers rarely, if ever, evaluate exactly to 0, especially after any kind of operation on them. Therefore, these data types would almost always evaluate to true and, hence, would be poor choices as a Boolean substitute.

Since C99, a _Bool type was added, which, when evaluated, will always evaluate to only 0 or 1. When we include the stdbool.h file, we are able to use the bool type as well; this is a bit cleaner than using the cumbersome...