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)