diy2.py

i=3
username = "python"
userpassword = "123456"
while True:
    if i>0:
        a = input("请输入用户名")
        b = input("请输入密码")
        i-=1
        if a == username and b == userpassword:
            print("登录成功!")
            break
        if a!=username:
            print("用户名错误!请重新输入")
            continue
        if b!=usdrpassword:
            print("密码错误")
    else:        
        print("不好意思你没机会里") 
        exit()  
print("欢迎来到贝尔编程!")