Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

142 Chapter 4 Loops
loop
end of loop
display result
13
14 // Keep reading data until the input is 0
15 int sum = 0;
16
17
while (data != 0) {
sum += data;
18
19 // Read the next data
20 System.out.print(
21 "Enter an integer (the input ends if it is 0): ");
22 data = input.nextInt();
23 }
24
25 System.out.println("The sum is " + sum);
26 }
27 }
Enter an integer (the input ends if it is 0):
Enter an integer (the input ends if it is 0):
Enter an integer (the input ends if it is 0):
Enter an integer (the input ends if it is 0):
The sum is 9
2
3
4
0
line# data sum output
12 2
15 0
iteration 1
iteration 2
iteration 3
17 2
22 3
17 5
22 4
17 9
22 0
25 The sum is 9
If data is not 0, it is added to sum (line 17) and the next item of input data is read (lines
20–22). If data is 0, the loop body is no longer executed and the while loop terminates. The
input value 0 is the sentinel value for this loop. Note that if the first input read is 0, the loop
body never executes, and the resulting sum is 0.
Caution
Don’t use floating-point values for equality checking in a loop control. Because floatingpoint
values are approximations for some values, using them could result in imprecise
counter values and inaccurate results.
Consider the following code for computing 1 + 0.9 + 0.8 + ... + 0.1:
double item = 1; double sum = 0;
while ( item != 0 ) { // No guarantee item will be 0
sum += item;
item -= 0.1;
}
System.out.println(sum);