In Chapter 5, we evaluated only one Boolean expression at a time to determine which of two alternative blocks of code should execute. However, often two (or more) Boolean expressions need to be evaluated to determine which block of code should execute. In the example in which you are eligible to vote only if the user is a citizen and at least 18 years old, both Boolean expressions must be true in order for the program to output that the user is eligible to vote. In another example, in which you get into a movie free if the user is either a senior citizen (65 years or older) or a child (12 or under), the program outputs that the user gets into the movie free if either Boolean expression is true.
This chapter covered two different approaches of evaluating two Boolean expressions to determine which code should execute. The first approach nested one if statement inside another. The second approach introduced three logical operators. The logical && (And) operator is used when both Boolean expressions must be true. The logical (Or) operator is used when either Boolean expression must be true. Finally, the logical ! (Not) operator inverts the value of a Boolean expression, from true to false, or false to true.
Finally, this chapter showed how you can use the switch statement as an alternative to an if / else or if / else if /else structure in programs that evaluate Boolean expressions using logical operators.