CONTROL STRUCTURES I: SELECTION - Java Programming: From Problem Analysis to Program Design - page 196

into the variable rate . The statement in Line 8 checks whether the value of the
variable hours is greater than 40.0 .If hours is greater than 40.0 , then the wages
are calculated by the statement in Line 9, which includes overtime payment; otherwise,
the wages are calculated by the statement in Line 11. The statement in Line 12 outputs
the wages.
Let's now consider more examples of if statements and examine some of the common
errors made by beginning programmers.
EXAMPLE 4-13
Consider the following statements:
if (score >= 90) //Line 1
grade = 'A'; //Line 2
System.out.println("The grade is " + grade); //Line 3
Here, you might think that because the statements in Lines 2 and 3 are aligned, both
statements are the action statements of the if statement. However, this is not the case.
The if statement acts on only one statement, which is grade = 'A'; . The output
statement executes regardless of whether (score >= 90) is true or false .
Example 4-14 illustrates another common mistake.
EXAMPLE 4-14
Consider the following statements:
if (score >= 60)
System.out.println("Passing");
System.out.println("Failing");
If the logical expression, score >= 60 , evaluates to false , the output would be
Failing . That is, this set of statements performs the same action as an else statement.
It will execute the second output statement rather than the first. For example, if the value
of score is 50 , these statements will output the following line:
Failing
However, if the logical expression, score >= 60 , evaluates to true , the program will
write both statements, giving an unsatisfactory result. For example, if the value of score
is 70 , these statements will output the following lines:
Passing
Failing