PHP supports C-style pre- and post-increment and decrement operators.
Table 10-4. 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:
1 2 <?php 3 echo "<h3>Postincrement</h3>"; 4 $a = 5; 5 echo "Should be 5: " . $a++ . "<br>\n"; 6 echo "Should be 6: " . $a . "<br>\n"; 7 8 echo "<h3>Preincrement</h3>"; 9 $a = 5; 10 echo "Should be 6: " . ++$a . "<br>\n"; 11 echo "Should be 6: " . $a . "<br>\n"; 12 13 echo "<h3>Postdecrement</h3>"; 14 $a = 5; 15 echo "Should be 5: " . $a-- . "<br>\n"; 16 echo "Should be 4: " . $a . "<br>\n"; 17 18 echo "<h3>Predecrement</h3>"; 19 $a = 5; 20 echo "Should be 4: " . --$a . "<br>\n"; 21 echo "Should be 4: " . $a . "<br>\n"; 22 ?> 23 |