zoukankan      html  css  js  c++  java
  • 2018.09.14python学习第四天part2

    流程控制之while循环

    1.什么是循环?(what)

    循环是指重复做某一件事

    2.为何要有循环?(why)

    为了让计算机能像人一样重复去做某一件事

    3.如何使用循环?(how)

    #语法一:while条件

    如:用户登录时信息输入错误是需要重新输入

    name_bd="tony"
    pwd_bd=123
    while True:
        name=input("please your name: ")
        pwd=input("plesse your password: ")
        if name == name_bd and pwd == pwd_bd:
            print("login successful")
        else:
            print("please input again")

    输入这段代码后,会发现无论你登录是否成功,都是无限循环登录,所以要让登录成功后就结束循环应该:

    name_bd="tony"
    pwd_bd="123"
    a=True
    while a:
        name=input("please your name: ")
        pwd=input("please your password: ")
        if name == name_bd and pwd == pwd_bd:
            print("login successful")
            a=False
        else:
            print("please input again")

    #语法二:while+break(break表示强制结束本层循环)

    name_bd="tony"
    pwd_bd="123"
    while True:
        name=input("please your name: ")
        pwd=input("plesse your password: ")
        if name == name_bd and pwd == pwd_bd:
            print("login successful")
            break
        else:
            print("please input again")

    这样也实现了登陆成功是终止循环

    #语法三:while+continue(continue表示停止本次循环,直接进入下一次)

    count=0
    while count<10:
        if count ==5:
            count+=1
            continue
        print(count)
        count+=1

    #语法四:while+else(else会在while循环没有被break终止的情况下执行)

    name_bd="tony"
    pwd_bd="123"
    count=0
    while count<=2:        
            name=input("please your name: ")
            pwd=input("plesse your password: ")
            if name == name_bd and pwd == pwd_bd:
                print("login successful")
                break
            else:
                print("please input again")
                count+=1
    else:
        print("输错次数太多,请稍后"

    #语法五:while循环的嵌套

    name_bd="tony"
    pwd_bd="123"
    count=0
    
    while count<=2:
        name=input("please your name: ")
        pwd=input("plesse your password: ")
        if name == name_bd and pwd == pwd_bd:
            print("login successful")
            while True:
                    print("1.浏览商品,2.添加购物车,3.支付,4.退出")
                    choice=input("请输入你的选择: ")
                    if choice=="1":
                            print("正在浏览商品")
                    if choice=="2":
                            print("正在添加购物车")
                    if choice=="3":
                            print("正在支付")
                    if choice=="4":
                            break
            break
        else:
            print("please input again")
            count+=1
    else:
        print("输错次数太多,请稍后")
  • 相关阅读:
    牛客练习赛51 D题
    Educational Codeforces Round 72 (Rated for Div. 2) C题
    Codeforces Round #583 (Div. 1 + Div. 2, based on Olympiad of Metropolises) C题
    Codeforces Round #583 (Div. 1 + Div. 2, based on Olympiad of Metropolises) A题
    Codeforces Round #583 (Div. 1 + Div. 2, based on Olympiad of Metropolises) A题
    Educational Codeforces Round 72 (Rated for Div. 2) B题
    Educational Codeforces Round 72 (Rated for Div. 2) A题
    《DSP using MATLAB》Problem 7.2
    《DSP using MATLAB》Problem 7.1
    《DSP using MATLAB》Problem 6.24
  • 原文地址:https://www.cnblogs.com/hello-yuanjing/p/9647701.html
Copyright © 2011-2022 走看看