12.⽤户登陆（三次输错机会）且每次输错误时显示剩余错误次数（提示：使⽤字符串格式化）...

a=1

b=2

while a<4:

    user=input('请输入账户')

    pswd=input('请输入密码')

    if user=='123' and pswd=='456':

        print('正确')

    else:

        print('你还有%s次机会'%(b))

    b=b-1

    a=a+1

转载于:https://www.cnblogs.com/zhangzhaohua/p/9839582.html