Python-流程控制之循环

# 1. while循环：条件循环
# I:基本语法
# while 条件：
#     代码1
#     代码2
#     代码3
#     ...

# 示范
# name_of_bk='huangdong'
# paw_of_bk='123'
#
# tag=True
# while tag:
#     inp_name=input('your name>>:')
#     inp_pwd=input('your password>>:')
#     if inp_name == name_of_bk and inp_pwd == paw_of_bk:
#         print('login successful')
#         tag=False
#     else:
#         print('username or password error')
#
#     print('emmmmmm')

# II: while+break:break代表结束本层循环
# 示范：
# while True:
#     print(1)
#     break
#     print(2)
#     print(3)

# name_of_bk='huangdong'
# paw_of_bk='123'
#
# while True:
#     inp_name=input('your name>>:')
#     inp_pwd=input('your password>>:')
#     if inp_name == name_of_bk and inp_pwd == paw_of_bk:
#         print('login successful')
#         break
#     else:
#         print('username or password error')
#
#     print('emmmmmm')

# III: while + continue: continue代表结束本次循环，直接进入下一次
# 示范
# count=1
# while count <6:
#     if count == 3:
#         count+=1
#         continue
#     print(count)
#     count+1

# 输错三次退出
# name_of_bk='huangdong'
# paw_of_bk='123'
#
# count=0
# while True:
#     if count == 3:
#         print('输错次数过多..')
#         break
#     inp_name=input('your name>>:')
#     inp_pwd=input('your password>>:')
#     if inp_name == name_of_bk and inp_pwd == paw_of_bk:
#         print('login successful')
#         break
#     else:
#         print('username or password error')
#         count+=1 #count=3 输错3次
#
#
#     print('emmmmmm')

# IV:while + else
# count=0
# while True:
#     if count == 10:
#         break
#     print(count)
#     count+=1
# else:
#     print('else的子代码块只有在while循坏没有被break打断的情况下才会执行')

# count=0
# while count <= 10:
#     print(count)
#     count+=1
#
# else:
#     print('else的子代码块只有在while循坏没有被break打断的情况下才会执行')


name_of_bk='huangdong'
pwd_of_bk='123'
count=0
tag=True
while tag:
    if count == 3:
        print('输错次数过多...')
        break
    inp_name=input('your name>>:')
    inp_paw=input('your password>>:')
    if inp_name == name_of_bk and inp_paw == inp_paw:
        print('login password')
        while tag:
            print('''
            0 退出
            1 购物
            2 支付
            3 查看购物车
            ''')
            cmd=input('>>:')
            if cmd == '0':
                tag=False
                continue
            if cmd == '1':
                print('购物...')
            elif cmd =='2':
                print('支付..')
            elif cmd == '3':
                print('购物车')
            else:
                print('输入错误的指令')

    else:
        print('username or password error')