Python——whilebreakcontinueelse

Posted 2020-11-19 小伍先森

1.while循环语句：

1  count = 0
2 while count <= 100:
3      print("loop ", count)
4      count += 1
5 print(‘----loop is ended----‘)

2.打印偶数：

 1 # 打印偶数
 2 # count = 0
 3 #
 4 # while count <= 100:
 5 #
 6 #     if count % 2 == 0: #偶数
 7 #         print("loop ", count)
 8 #
 9 #     count += 1
10 #
11 #
12 # print(‘----loop is ended----‘)

3.第50次不打印，第60-80打印对应值 的平方

 1 count = 0
 2 
 3 while count <= 100:
 4 
 5     if count == 50:
 6         pass #就是过。。
 7 
 8     elif count >= 60 and count <= 80:
 9         print(count*count)
10 
11     else:
12         print(‘loop ‘, count)
    
       count+=1

4.死循环

1 count = 0
2 
3 while True:
4     print("forever 21 ",count)
5     count += 1

5.循环终止语句：break&continue

break：用于完全结束一个循环，跳出循环体执行循环后面的语句

continue:不会跳出整个循环，终止本次循环，接着执行下次循环，break终止整个循环

 

1 # break 循环
2 # count=0
3 # while count<=100:
4 #     print(‘loop‘,count)
5 #     if count==5:
6 #         break
7 #     count+=1
8 # print(‘-----out of while loop---‘)

 

1 #continue 循环
2 count=0
3 while count<=100:
4     print(‘loop‘,count)
5     if count==5:
6         continue
7     count+=1
8 # print(‘-----out of while loop---‘)   #一直打印5
9 #continue 跳出本次循环，不会执行count+=1，count一直为5

例1：让用户猜年龄

1 age = 26
2 user_guess = int(input("your guess:"))
3 if user_guess == age :
4     print("恭喜你答对了，可以抱得傻姑娘回家！")
5 elif user_guess < age :
6     print("try bigger")
7 else :
8     print("try smaller")

例2：用户猜年龄升级版，让用户猜年龄，最多猜3次，中间猜对退出循环

 1 count = 0
 2 age = 26
 3 
 4 while count < 3:
 5 
 6     user_guess = int(input("your guess:"))
 7     if user_guess == age :
 8         print("恭喜你答对了，可以抱得傻姑娘回家！")
 9         break
10     elif user_guess < age :
11         print("try bigger")
12     else :
13         print("try smaller")
14 
15     count += 1

例3：用户猜年龄继续升级，让用户猜年龄，猜3次，如果用户3次都错，询问用户是否还想玩，如果为y,则继续猜3次，以此往复【注解提示：相当于在count=3的时候询问用户，如果还想玩，等于把count变为0再从头跑一遍】

count = 0
age = 26

while count < 3:

    user_guess = int(input("your guess:"))
    if user_guess == age :
        print("恭喜你答对了，可以抱得傻姑娘回家！")
        break
    elif user_guess < age :
        print("try bigger")
    else :
        print("try smaller")

    count += 1

    if count == 3:
        choice = input("你个笨蛋，没猜对，还想继续么?(y|Y)")
        if choice == ‘y‘ or choice == ‘Y‘:
            count = 0

6.while&else：while 后面的else的作用是，当while循环正常执行完，中间没有被break中止的话，就会执行else后的语句【else 检测你的循环过程有没有中止过（当你的循环代码比较长的时候）】

 

1  count=0
2 # while count <=5:
3 #     count+=1
4 #     print(‘loop‘,count)
5 #
6 # else:
7 #     print(‘循环正常执行完啦‘)
8 # print(‘-----out of while loop----‘)

1 count=0
2 while count<=5:
3     print(‘loop‘,count)
4     if count==3:
5         break
6     count+=1
7 else:
8     print(‘loop is done‘)