Java Reference
In-Depth Information
4.3
x = x +
1
;
x += 1;
++x;
x++;
4.4
a)
z = x++ + y;
b)
if
(count >
10
)
System.out.println(
"Count is greater than 10"
);
c)
total -= --x;
d)
q %= divisor;
q = q % divisor;
4.5
a)
int
sum =
0
;
b)
int
x =
1
;
c)
sum += x;
or
sum = sum + x;
d)
System.out.printf(
"The sum is: %d%n"
, sum);
4.6
The program is as follows:
1
// Exercise 4.6: Calculate.java
2
// Calculate the sum of the integers from 1 to 10
3
public class
Calculate
4
{
5
public static void
main(String[] args)
6
{
7
int
sum =
0
;
8
int
x =
1
;
9
10
while
(x <=
10
)
// while x is less than or equal to 10
11
{
12
sum += x;
// add x to sum
13
++x;
// increment x
14
}
1
16
System.out.printf(
"The sum is: %d%n"
, sum);
17
}
18
}
// end class Calculate
The sum is: 55
4.7
product
=
25
,
x
=
6
4.8
a) Error: The closing right brace of the
while
statement's body is missing.
Correction: Add a closing right brace after the statement
++c;
.
b) Error: The semicolon after
else
results in a logic error. The second output statement
will always be executed.
Correction: Remove the semicolon after
else
.
4.9
The value of the variable
z
is never changed in the
while
statement. Therefore, if the loop-
continuation condition
(z
>=
0
) is true, an infinite loop is created. To prevent an infinite loop from
occurring,
z
must be decremented so that it eventually becomes less than 0.
Exercises
4.10
Compare and contrast the
if
single-selection statement and the
while
repetition statement.
How are these two statements similar? How are they different?
