php5中抽象类的小例子

3. /**

4. * 定义与使用php抽象类
5. * edit: bbs.it-home.org
6. */
7. abstract class Number {
8. private $value;
9. abstract public function value();
10. public function reset() {
11. $this->value = NULL;
12. }
13. }

14. class Integer extends Number {

15. private $value;
16. public function value() {
17. return (int)$this->value;
18. }
19. }

20. $num = new Integer; /* Okay */

21. $num2 = new Number; /* This will fail */
22. ?>

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