Java Reference
In-Depth Information
You also need the following code, to be included after the
while
loop, in case the user
cannot guess the correct number in five tries:
if
(!done)
System.out.println("You lose! The correct "
+ "number is " + num);
We leave it as an exercise for you to write a complete Java program to implement the
Guessing the Number game in which the user has, at most, five tries to guess the number.
(See Programming Exercise 16 at the end of this chapter.)
As you can see from the preceding
while
loop, the logical expression in a
while
statement can be complex. The main objective of a
while
loop is to repeat certain
statement(s) until certain conditions are met.
Next, consider the following
while
loop:
int
count = 0;
while
(count++ < 5)
System.out.println("Iteration: " + count);
System.out.println("The value of count after the while loop: " + count);
Note that the loop control variable
count
is initialized before the
while
loop and its
value is updated in the
while
loop test condition (logical expression). The expression
count++ < 5
uses the post-increment operator. So first the value of
count
is used to
evaluate the expression and then the value of
count
is incremented. The output of the
previous
while
loop is:
Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
Iteration: 5
The value of count after the while loop: 6
Now consider the following
while
loop:
int
count = 0;
while
(++count < 5)
System.out.println("Iteration: " + count);
System.out.println("The value of count after the while loop: " + count);
In this
while
loop, the expression
++count < 5
uses the pre-increment operator. So first
the value of
count
is incremented and then its value is used to evaluate the expression.
The output of the previous
while
loop is:
Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
The value of count after the while loop: 5
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