PHP supports C-style pre- and post-increment and decrement
operators.
Note:
The increment/decrement operators do not affect boolean values.
Decrementing NULL values has no effect too, but incrementing them
results in 1.
Table 15-6. Increment/decrement Operators
| Example | Name | Effect |
|---|
| ++$a | Pre-increment | Increments $a by one, then returns $a. |
| $a++ | Post-increment | Returns $a, then increments $a by one. |
| --$a | Pre-decrement | Decrements $a by one, then returns $a. |
| $a-- | Post-decrement | Returns $a, then decrements $a by one. |
Here's a simple example script:
PHP follows Perl's convention when dealing with arithmetic operations
on character variables and not C's. For example, in Perl 'Z'+1 turns
into 'AA', while in C 'Z'+1 turns into '[' ( ord('Z') == 90, ord('[') == 91 ).
Note that character variables can be incremented but not decremented and
even so only plain ASCII characters (a-z and A-Z) are supported.
Example 15-4. Arithmetic Operations on Character Variables
<?php
$i = 'W';
for ($n=0; $n<6; $n++) {
echo ++$i . "\n";
}
?>
|
The above example will output: |
Incrementing or decrementing booleans has no effect.
