Python_No.4 if

一、
# ！/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Hugolinhj



_username = "hugolin"
_password = "qq1234"
#定义用户密码
username = input("username:")
password = input("password:")
#输入用户密码

if _username == username and password == password:
    print("welcome user {name} login....".format(name=username))
else:
    print("Invalid username or password!")
#判断输入字符是否正确。

###############################    注：换行字节缩进   #################



age_of_oldboy = 56

guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
    print("yes,you got it.")
elif guess_age > age_of_oldboy:
    print("think smaller...")
else:
    print("think bigger!")