【Python3】条件语句与循环语句

发布时间:2019-10-16 17:29:11编辑:auto阅读(580)

    1 条件语句

    • 例1:
    if 条件:
        ...
    else:
        ...
    • 应用
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    username = input("请输入用户名:")
    password = input("请输入密码:")
    
    
    if username  == 'fcc' and password == '123':
        print("欢迎登陆!")
    else:
        print("用户名或密码错误!")
    
    • 例2:
    if 条件:
        ...
    elif 条件:
        ...
    else:
        ...   
    • 应用:
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    sex = input("请输入你的性别:")
    
    if sex == "男":
        print("傻x,自己性别都忘了!")
    elif sex == "女":
        print("...你在想想,你忘了你已经做了手术了吗...")
    else:
        print("人妖.......")

    2 循环语句

    • while
    while 条件:
        continue # 开始下一次循环
        break # 跳出所有循环
    • 例:
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    i = 0
    while i < 3:
        username = input("请输入用户名:")
        password = input("请输入密码:")
        if username == 'fcc' and password == '123':
            print("欢迎登陆!")
            break
        else:
            print('用户名或密码错误')
            i += 1

    3 练习

      1. 使用while循环输入 1 2 3 4 5 6 8 9 10
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    i = 1
    while True:
        if i == 7:
            i += 1
            continue
        print(i)
        i += 1
        if i == 11:
            break
      1. 求1-100的所有数的和
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    value = 0
    i = 1
    while i < 101:
        value = value + i
        i += 1
    print(value)
      1. 输出 1-100 内的所有奇数
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    i = 1
    
    while i < 101:
        if i % 2 == 1:
            print(i)
        i += 1
      1. 输出 1-100 内的所有偶数
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    i = 1
    
    while i < 101:
        if i % 2 == 0:
            print(i)
        i += 1
      1. 求1-2+3-4+5 ... 99的所有数的和
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    value = 0
    i = 1
    
    while i < 100:
        if i % 2 == 1:
            value = value + i
            i += 1
        elif i % 2 == 0:
            value = value - i
            i +=1
    print(value)
      1. 用户登陆(三次机会重试)
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author:Chuncheng.Fan <xmzncc@gmail.com>
    
    i = 0
    
    while i < 3:
        username = input("请输入用户名:")
        password = input("请输入密码:")
        if username == 'fcc' and password == '123':
            print("欢迎登陆!")
            break
        else:
            print("用户名或密码错误")
            i += 1

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