Java Reference
In-Depth Information
Note that in the temperature conversion program, the operands to the division
operation are floating point literals to ensure that the fractional part of the num-
ber is kept. The precedence rules dictate that the multiplication happens before
the addition in the final conversion computation.
The
TempConverter
program is not very useful because it converts only one
data value that we included in the program as a constant (24 degrees Celsius).
Every time the program is run it produces the same result. A far more useful ver-
sion of the program would obtain the value to be converted from the user each
time the program is executed. Interactive programs that read user input are dis-
cussed later in this chapter.
There are two other useful arithmetic operators. The
increment operator
(
++
)
adds 1 to any integer or floating point value. The two plus signs that make up
the operator cannot be separated by white space. The
decrement operator
(
--
) is
similar except that it subtracts 1 from the value. They are both unary operators
because they operate on only one operand. The following statement causes the
value of
count
to be incremented:
count++;
The result is stored back into the variable
count
. Therefore it is functionally
equivalent to the following statement, which we discussed in the previous section:
count = count + 1;
The increment and decrement operators can be applied after the variable
(such as
count++
or
count--
), creating what is called the
postfix form
of the
operator. They can also be applied before the variable (such as
++count
or
--count
), in what is called the
prefix form.
When used alone in a statement,
the prefix and postfix forms are functionally equivalent. That is, it doesn't
matter if you write
count++;
or
++count;
However, when such a form is written as a statement by itself, it is usually written
in its postfix form.
When the increment or decrement operator is used in a larger expression, it can
yield different results depending on the form used. For example, if the variable
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