## 第一章 循环语句

if 条件：

代码

else：

print（‘ ’）

if ...else...

if 条件：

代码

elif 条件：

代码

elif 条件：

代码

else：

代码

While 循环

count = 0

while count<=100:

print("loop",count)

count+=1

count=0

while True:

print('aisfioasudfiaus',count)

count+=1

break

count=0

while count<100:

print('loop', count)

if count ==5:

break

count+=1

print('-----out of while loop ------')

continue

count=0

while count <=100:

count+=1

if count>5 and count <95:

continue

print("loop", count)

print("----out of while loop ----")

while ... else ...

count=0

while <=5:

count+=1

print("loop",count)

else:

print('')

print("-----------")

age_of_oldboy=8

age=input('请输入年龄>>: ')

if age==age_of_oldboy:

print('正确')

break

else:

print('错误，请重新输入）

age=input('请输入年龄>>: ')

if age==age_of_oldboy:

print('正确')

break

else:

print('错误，请重新输入）

age=input('请输入年龄>>: ')

if age==age_of_oldboy:

print('正确')

break

else:

print('错误超过三次，退出）

`count=0age_of_oldboy=8while count<3:    age = int(input('请输入年龄>>: '))    if age == age_of_oldboy:        print('正确')        break    else:        print('错误')    count += 1    if count==3:        agent=input('错误次数超过三次,继续按y，否则按n')        if agent== 'y'or agent == 'Y':            count=0            continue        elif agent == 'N' or agent == 'n':            break登陆接口用户3次认证失败后，退出程序，再次启动程序尝试登陆时，还是锁定状态（用户锁定状态存在文件里）`
`dic={'user1':{'psw':'123','count':0},     'user2':{'psw':'123','count':0},     'user3':{'psw':'123','count':0},     }while True:    name=input('请输入用户名>: ')    if  not name in dic:        print('请重试')        continue    with open('user.txt','r') as read_f:        bb=read_f.read().splitlines()        if name in bb:            print('账户已锁定')            continue    psw=input('请输入密码>: ')    if dic[name]['count'] >2:        print('锁定')        with open('user.txt', 'a+') as write_f:            write_f.write(name)            write_f.write('\n')        break    if psw ==dic[name]['psw']:        print('登陆成功')        break    else:        print('请重试')        dic[name]['count']+=1        continue`