diy2.py

username = "python"
userpassword = "123456"
i = 3
while True:
    if i>0:
        name = input("请输入用户名:")
        password = input("请输入密码:")
        i = i - 1
        if name != username:
            print("用户名错误!")    
            continue
        if password != userpassword:    
            print("密码错误!")
            continue              
        print("登录成功!")
        break
    else:
        print("账号已被锁定")
        exit()
print("欢迎来到贝尔编程!")