import random

secretNumber = random.randint(1, 20)

print(' I am thinking of number between 1 and 20.'')

for guessesTimes in range(1, 6):

    print('take a guess.')

    guess = int(input())

    if guess < secretNumber:

        print('Your guess is too low.')

    elif guess > secretNumber:

         print('Your guess is too high.')

    else:

        break

if guess == secretNumber:    # guess 继承循环中的变量；即for循环中的变量为全局变量。

    print('Good job! You guessed my number in' + str(guessesTimes) + 'guesses! ')

else:

    print('Nope. The number I was thinking of was' + str(scretNumber))

以上代码扩展为登录页面的输入账号/密码的校验

1）暴力输入最多5次；

2）账号或密码输入错误时，提示“账号或密码输入错误，还剩(5-n)次机会，请重新输入！”

3）输入错误次数等于5次时，提示“错误输入次数已达上限5次，账户锁定！”

4）输入成功时，提示“恭喜你，登录n次后，成功了。”