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  • Day_02-Python的循环结构

    循环结构

    应用场景

      如果在程序中我们需要重复的执行某条或某些指令,例如用程序控制机器人踢足球,如果机器人持球而且还没有进入射门范围,那么我们就要一直发出让机器人向球门方向奔跑的指令。当然你可能已经注意到了,刚才的描述中其实不仅仅有需要重复的动作,还有我们上一个章节讲到的分支结构。再举一个简单的例子,比如在我们的程序中要实现每隔1秒中在屏幕上打印一个"hello, world"这样的字符串并持续一个小时,我们肯定不能够将print('hello, world')这句代码写上3600遍,如果真的需要这样做那么编程的工作就太无聊了。因此,我们需要了解一下循环结构,有了循环结构我们就可以轻松的控制某件事或者某些事重复、重复、再重复的发生。在Python中构造循环结构有两种做法,一种是for-in循环,一种是while循环。

    for-in循环

    练习:

    1.

    # for循环 while用于死循环
    import time
    sum_ = 0
    s = time.time()
    for i in range(10000000):
    sum_ *= i
    e = time.time()
    print(e - s)
     
    # for i in range(1,101,2):
    # print(i)

    # 银行卡密码
    # pwd = '123456'
    # user_pwd = input('请输入密码:')
    # count = 0
    # for i in range(5):
    # count += 1
    # if user_pwd == pwd:
    # print('Login!')
    # break
    # elif count <= 2:
    # print('Error')
    # user_pwd = input('请输入密码:')
    # else:
    # print('锁定')
    # break
     
     
    # 验证码
    # import numpy as np
    # import random
    # computer1 = ''
    # for i in range(4):
    # computer = random.choice('abcdefghijklmnopqrstuvwxyz')
    # computer1 += computer
    # print(computer1,end='')
    # user_check = input('请输入验证码:')
    # if user_check == computer1:
    # print('验证成功')
    # else:
    # print('验证失败')

    # 验证码2
    # import random
    # computer1 = ''
    # for i in range(4):
    # computer = random.choice('abcdefghijklmnopqrstuvwxyz1234567890')
    # computer1 += computer
    # print(computer1,end='')
    # for j in range(3):
    # user_check = input('请输入验证码:')
    # if user_check == computer1:
    # print('验证成功')
    # break
    # else:
    # print('验证失败')

    # 密码爆破 爆破一个6位数的银行卡密码

    # 银行卡密码 while
    # pwd = '123456'
    # user_pwd = input('请输入密码:')
    # i = 0
    # while i <= 1:
    # i += 1
    # if user_pwd == pwd:
    # print('Login')
    # break
    # else:
    # print('Error,重新输入')
    # user_pwd = input('请输入密码:')

    # 验证码 while
    # import random
    # computer1 = ''
    # i = 0
    # while i <= 3:
    # i += 1
    # computer = random.choice('abcdefghijklmnopqrstuvwxyz1234657890')
    # computer1 += computer
    # print(computer1,end='')
    # user_check = input('请输入验证码:')
    # if user_check == computer1:
    # print('验证成功')
    # else:
    # print('验证失败')

    # 阶乘
    # m = float(input('m = '))
    # n = float(input('n = '))
    # mn = m - n
    # fm = 1
    # while m != 1:
    # fm *= m
    # m -= 1
    # fn = 1
    # while n != 1:
    # fn *= n
    # n -= 1
    # fmn = 1
    # while mn != 1:
    # fmn *= mn
    # mn -= 1
    # print(fm // fn // fmn)

    # 函数
    # def defineName([params]):
    # ........
    # ........
    # return..
    # 带参函数
    # def Print(name):
    # print('%s say:hello'%name)
    # Print('zqq')

    # m = int(input('m = '))
    # n = int(input('n = '))
    # fm = 1
    # for num in range(1, m + 1):
    # fm *= num
    # fn = 1
    # for num in range(1, n + 1):
    # fn *= num
    # fmn = 1
    # for num in range(1, m - n + 1):
    # fmn *= num
    # print(fm // fn // fmn)
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  • 原文地址:https://www.cnblogs.com/KAJIA1/p/11279174.html
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