Day1：循环语句（While，For）

一、while循环

　　while 条件：

　　　　条件为真执行的语句

　　esle:

　　　　条件为假执行的语句

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
count = 0
while count < 100:
    print("Count:",count)
    count += 1

　　猜年龄升级版

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 # Author:Hiuhung Wan
 4 age_of_MrWang = 48
 5 count = 0
 6 while count < 3:
 7     guess_age = int(input("Enter the age of Mr Wang:"))
 8     if guess_age == age_of_MrWang:
 9         print("Yes,you got it!")
10         break
11     elif guess_age < age_of_MrWang:
12         print("Think bigger!")
13     else:
14         print("Think smaller!")
15     count += 1
16     # if count == 3:
17     #     print("You have tried too many times...Fuck off!")
18 else:
19     print("You have tried too many times...Fuck off!")

View Code

二、For循环

　　for i in range (xx):

　　　　语句

　　else:

　　　　上面循环里的语句正常走完了后，才执行这里的语句

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
for i in range(10):
    print("loop",i)

　　再次优化一下猜年龄小程序

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 # Author:Hiuhung Wan
 4 age_of_MrWang = 48
 5 for i in range (3):
 6     guess_age = int(input("Enter the age of Mr Wang:"))
 7     if guess_age == age_of_MrWang:
 8         print("Yes,you got it!")
 9         break
10     elif guess_age < age_of_MrWang:
11         print("Think bigger!")
12     else:
13         print("Think smaller!")
14 else:
15     print("You have tried too many times...Fuck off!")

View Code

三、for循环步长问题

　　range里可以设置，默认是1

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
for i in range(0,10,2):   #步长是2
    print("loop",i)

四、猜年龄小程序加入继续玩模式

　　思路：猜了三次还没有猜对，提示是否继续猜，如果按n就退出程序，其他键就继续猜。同时判断输入是否为数字

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
age_of_MrWang = 48
count = 0  #计数器
while count < 3:
    guess_age = input("Enter the age of Mr Wang:")
    if guess_age.isdigit(): #输入了数字
        guess_age = int(guess_age)
        if guess_age == age_of_MrWang:
            print("Yes,you got it!")
            break  #猜对了，退出while循环
        elif guess_age < age_of_MrWang:
            print("Think bigger!")
        else:
            print("Think smaller!")
        count += 1
        if count == 3:
            continue_confirm = input("Do you want to keey guessing?")
            if continue_confirm != "n":
                count = 0  # 计数器清零
    else:
        print("Please enter a number!")

五、break与continue

　　continue:跳出本次循环（或者说：结束当前循环），继续下一次循环

　　break:结束整个循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
for i in range(0,10):
    if i < 5:
        print("loop",i)
    else:
        continue
    print("The variable i loops once")

六、for循环嵌套

　　注意break的使用

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hiuhung Wan
for i in range(10):
    print("-------",i)
    for j in range (10):
        print(j)
        if j > 5:
            break  #结束当前循环（j），继续下一次循环