while 循环
- 只要循环语句中的条件布尔值为True ，就会不停的执行下面的代码块 命令。
- while循环是无边界循环，for in 循环是有边界循环
- 和 if 语句的相似点都是检查一个布尔表达式的真假，if 语句是执行一次，while 循环是执行完跳回到while 顶部，如此重复，直到布尔值为假False
- 尽量少用 while 循环，大部分时候用 for in 循环是更好选择
1 i = 0 # 第一种while 循环 写法
2 numbers = [] # 把空数组赋值给变量numbers
3
4 while i < 6: # 进入while 循环 当i<6:
5 print(f'At the top is {i}') # 打印 i的头部数
6 numbers.append(i) # 变量numbers 尾部追加 i 数字
7
8 i+=1 # i 每次自增1
9 print("Numbers now:",numbers) # 记得加逗号//打印 数组现在：
10 print(f"At the bottom is {i}") # 打印 i的底部数
11
12 print("The numbers :") # 打印 这个数字是：
13 for num in numbers: # 用for循环来循环数组numbers
14 print(num) # 打印 num 变量
15
16
17
18
19 shuzu = [] # 第二种for in 循环语句改写
20
21 for t in range(0,6):
22 print(f"top of t:{t}")
23 shuzu.append(t)
24 print(f"shuzu:",shuzu)
25 t+=1
26 print(f"bottom of t:{t}")
27
28 print(f"The shuzu:")
29 for shu in shuzu:
30 print(shu)
PS C:\Users\Administrator\lpthw> python ex33.py
At the top is 0
Numbers now: [0]
At the bottom is 1
At the top is 1
Numbers now: [0, 1]
At the bottom is 2
At the top is 2
Numbers now: [0, 1, 2]
At the bottom is 3
At the top is 3
Numbers now: [0, 1, 2, 3]
At the bottom is 4
At the top is 4
Numbers now: [0, 1, 2, 3, 4]
At the bottom is 5
At the top is 5
Numbers now: [0, 1, 2, 3, 4, 5]
At the bottom is 6
The numbers :
0
1
2
3
4
5
top of t:0
shuzu: [0]
bottom of t:1
top of t:1
shuzu: [0, 1]
bottom of t:2
top of t:2
shuzu: [0, 1, 2]
bottom of t:3
top of t:3
shuzu: [0, 1, 2, 3]
bottom of t:4
top of t:4
shuzu: [0, 1, 2, 3, 4]
bottom of t:5
top of t:5
shuzu: [0, 1, 2, 3, 4, 5]
bottom of t:6
The shuzu:
0
1
2
3
4
5
