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++;