HTML and CSS Reference

In-Depth Information

Now you have four ways to add 1 to the value of a variable:

•

x += 1;

•

x += ;

•

x++;

•

++x;

and four ways to subtract 1 from the value of a variable:

•

x = x - 1;

•

x -= 1;

•

x- -;

•

- -x;

Refer to Table 5.4. In section “Loops” on page 131, you'll see these operators are com-

monly used to increment or decrement loop counters.

Table 5.4
Autoincrement and Autodecrement Operators

Operator

Function

What It Does

Example

++x

Pre-increment

Adds 1 to
x

x = 3; x++;

x
is now
4

x++

Post-increment

Adds 1 to
x

x = 3; ++x;

x
is now
4

- -x

Pre-decrement

Subtracts 1 from
x

x = 3; x - -;

x
is now
2

x- -

Post-decrement

Subtracts 1 from
x

x = 3; - -x;

x
is now
2

Autoincrement and Autodecrement Operators and Assignment.
The place-

ment of the operators does make a difference in more complex expressions, especially

when part of an assignment; for example,
y = x++
is not the same as
y = ++x
.

Start with:
y = 0 ; x = 5;

before

0

y

5

x

Pre-increment

after

6

y

6

x

y = ++x;

before

0

y

5

x

Post-increment

after

5

y

6

x

y = x++;