54 lines
1.6 KiB
Markdown
54 lines
1.6 KiB
Markdown
---
|
||
title: While Loop Statements
|
||
localeTitle: 循环语句
|
||
---
|
||
## 循环语句
|
||
|
||
Python使用`while`循环与其他流行语言类似。 `while`循环计算条件,然后在条件为真时执行代码块。代码块重复执行,直到条件变为false。
|
||
|
||
基本语法是:
|
||
|
||
```python
|
||
counter = 0
|
||
while counter < 10:
|
||
# Execute the block of code here as
|
||
# long as counter is less than 10
|
||
```
|
||
|
||
一个例子如下所示:
|
||
|
||
```python
|
||
days = 0
|
||
week = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
|
||
while days < 7:
|
||
print("Today is " + week[days])
|
||
days += 1
|
||
```
|
||
|
||
输出:
|
||
```
|
||
Today is Monday
|
||
Today is Tuesday
|
||
Today is Wednesday
|
||
Today is Thursday
|
||
Today is Friday
|
||
Today is Saturday
|
||
Today is Sunday
|
||
```
|
||
|
||
逐行解释上述代码:
|
||
|
||
1. 变量'days'设置为值0。
|
||
2. 将变量周分配给包含一周中所有日期的列表。
|
||
3. while循环开始
|
||
4. 代码块将被执行,直到条件返回'true'。
|
||
5. 条件是'days <7',其中rougly说运行while循环直到变量天数小于7
|
||
6. 所以当days = 7时,while循环停止执行。
|
||
7. days变量在每次迭代时都会更新。
|
||
8. 当while循环第一次运行时,“Today is Monday”行被打印到控制台上,变量days变为等于1。
|
||
9. 由于变量天数等于1,小于7,因此再次执行while循环。
|
||
10. 它一次又一次地进行,当控制台打印出“今天是星期天”时,变量天数现在等于7,而while循环停止执行。
|
||
|
||
#### 更多信息:
|
||
|
||
* [Python `while`语句文档](https://docs.python.org/3/reference/compound_stmts.html#the-while-statement) |