Basic Pascal Tutorial/Chapter 5/Subranges/zh CN: what changed
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Title: Basic Pascal Tutorial/Chapter 5/Subranges/zh CN
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| 1 | + | 5B - 子界类型 (原作者: Tao Yue, 状态: 未更改) | |
| 2 | + | ||
| 3 | + | 如果我们定义一个变量i为integer类型，那么i的值在微型机系统的pascal中，使用2字节的定义表示法，取值范围为-32768～32767；而事实上，每个程序中所用的变量的值都有一个确定的范围；例如：人的年龄一般不超过150；一个班级的学生不超过100人；一年中的月数不超过12；一月中的天数不超过31，等等。 | |
| 4 | + | ||
| 5 | + | 如果我们能在程序中对所用的变量的值域作具体规定的话，就便于检查出那些不合法的数据，这就能更好地保证程序运行的正确性；而且在一定程度上还会节省内存空间。 | |
| 6 | + | ||
| 7 | + | ``` pascal | |
| 8 | + | 最低值 .. 最高值 | |
| 9 | + | ``` | |
| 10 | + | ||
| 11 | + | `其中最低值称为子界的下界，最高值称为子界的上界。` | |
| 12 | + | ||
| 13 | + | `下界和上界必须是同一顺序类型（该类型称为子界类型的基类型），且上界的序号必须大于下界的序号。` | |
| 14 | + | ||
| 15 | + | 如，你声明一周以及一周天数： | |
| 16 | + | ||
| 17 | + | ``` pascal | |
| 18 | + | type | |
| 19 | + | DaysOfWeek = (Sunday, Monday, Tuesday, Wednesday, | |
| 20 | + | Thursday, Friday, Saturday); | |
| 21 | + | DaysOfWorkWeek = Monday..Friday; | |
| 22 | + | ``` | |
| 23 | + | ||
| 24 | + | 你也可以使用字符或整数在子界类型中。 | |
| 25 | + | ||
| 26 | + | ### 参考 | |
| 27 | + | ||
| 28 | + | [算法与程序设计：PASCAL枚举、子界类型](http://xkwq.e21.cn/content.php?id=61691) | |
| 29 | + | ||
| 30 | + | | | | | | |
| 31 | + | |----|----|----| | |
| 32 | + | | [[Basic Pascal Tutorial/Chapter 5/Enumerated types/zh CN|上一页]] | [[Basic Pascal Tutorial/Contents/zh CN|目录]] | [[Basic Pascal Tutorial/Chapter 5/1-dimensional arrays/zh CN|下一页]] | | |
| 33 | + | ||
| 34 | + | --- | |
| 35 | + | *From the Free Pascal wiki, page "Basic Pascal Tutorial/Chapter 5/Subranges/zh CN", as it stood on 2022-08-20 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |