python中的程序中断、for循环和while循环

一时失言乱红尘 2021-12-23 08:05 456阅读 0赞

## 1.程序中断 ##

break:跳出整个循环，不会再执行循环后面的内容  
continue:跳出本次循环，continue后面的代码不再执行，但是循环依然继续  
exit():结束程序的运行

for i in range(10):
        if i == 5:
            # continue
            # break
            exit()
            print('hello')
        print(i)
    
    print('hello python')

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 1]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 2]

## for循环 ##

for循环语法：

for 变量 in range(x):  
循环需要执行的代码

range(stop): 0 ~ stop-1  
range(start,stop): start ~ stop-1  
range(start,stop,step): start ~ stop-1 step(步长)

1.用户输入一个整型数，求该数的阶乘，例如5 = 5 \* 4 \* 3 \* 2 \* 1

num = int(input('Num:'))
    
    res = 1
    
    for i in range(1,num+1):
        res *= i
    
    print('%d的阶乘结果为: %d' %(num,res))

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 3]  
2.求1~100之间的所有偶数求和。

sum = 0
    for i in range(2,101,2):
        sum += i
    
    print(sum)

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 4]

3.有1，2，3，4四个数字。求四个数字能生成多少个互不相同且无重复数字的三位数(不能含有类似122 133)。

count = 0
    
    for i in range(1,5):
        for j in range(1,5):
            for k in range(1,5):
                if i != j and j !=k and k != i:
                    print(i * 100 + j * 10 + k)
                    count += 1
    
    print('生成%d个无重复数字的三位数' %count)

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 5]

4.用户登陆系统，要求：输入用户名和密码；判断是否正确(name = ‘root’，passwd = ‘westos’)；登录仅有3次及会，超过3次，报错。

for i in range(3):
        name = input('用户名: ')
        passwd = input('密码: ')
        if name == 'root' and passwd == 'westos':
            print('登录成功！')
            break
        else:
            print('登录失败')
            print('您还剩余%d次机会' %(2-i))
    
    else:
        print('失败超过3次，请稍后再试！')

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 6]  
5.给定两个数，求这两个数的最小公倍数和最大公约数。

#1.接收两个数字
    num1 = int(input('Num1: '))
    num2 = int(input('Num2: '))
    
    #2.找出两个数中的最小值
    min_num = min(num1,num2)
    
    #3.最大公约数范围在1～min_num之间
    for i in range(1,min_num+1):
        if num1 % i ==0 and num2 %i ==0:
            gys = i
    
    #4.最小公倍数
    gbs = (num1*num2 / gys)
    
    print('%d和%d的最大公约数为: %d' %(num1,num2,gys))
    print('%d和%d的最小公倍数为: %d' %(num1,num2,gbs))

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 7]

## 3.while循环 ##

while 条件:  
条件满足时，做的事情1  
条件满足时，做的事情2

#1.定义计数器
    i = 0
    
    #2.开始循环
    while i < 3:
        #循环内需要做的事情
        print('hello python')
    
        #处理计数器
        i += 1

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 8]  
一直循环

while True:
        print('hello python')

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 9]  
**练习：**

1.求1～100的和

i = 0
    sum = 0
    
    while i <= 100:
        sum += i
    
        i += 1
    
    print('0~100之间的数字求和结果为: %d' %sum)

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 10]2.用户登陆三次失败提示。

trycount = 0
    
    while trycount < 3:
        name = input('用户名: ')
        passwd = input('密码: ')
        if name == 'root' and passwd == 'westos':
            print('登录成功！')
            break
        else:
            print('登录失败')
            print('您还剩余%d次机会' %(2-trycount))
            trycount += 1
    else:
        print('失败超过3次，请稍后再试！')

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 11]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 12]  
3.猜数字

1.随机生成1～100的数字  
2.5次机会  
3.too big  
4.too small  
5.恭喜，并退出循环

import random
    
    trycount = 0
    computer = random.randint(1,100)
    print(computer)
    
    while trycount < 5:
        player = int(input('Num: '))
        if player > computer:
            print('too big')
            trycount += 1
        elif player < computer:
            print('too small')
            trycount += 1
        else:
            print('恭喜')
            break

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 13]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 14]4.在控制台连续输出五行\*,每行依次递增,即使用while循环显示出以下图形：

*****
    ****
    ***
    **
    *

row = 5
    while row >= 1:
        col = 1
        while col <= row:
            print('*',end='')
            col += 1
        print('')
        row -= 1

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 15]

*
    **
    ***
    ****
    *****

row = 1
    while row <= 5:
        col = 1
        while col <= row:
            print('*',end='')
            col += 1
        print('')
        row += 1

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 16]  
5.在python的IDE中输出类似于shell界面中的内容并且可以成功使用命令。

import os
    for i in range(1000):
        cmd = input('[kiosk@python ~]$ ')
        if cmd:
            if cmd == 'exit':
                print('logout')
            else:
                os.system(cmd)
        else:
            continue

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg4OTYxNg_size_16_color_FFFFFF_t_70 17]

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