分支

if 条件:

　　　　满足条件后执行缩进的代码

_username = "dongdong"

_password  = "abc123"

username = input("username:")

password = inout("password:")

if username == _usrrname and password == _password:

　　print("welcome,"_username)

else:

　　print("worong username or password")

 

小练习:

1

name = input("Your name:")
sex = input("Your sex:")
if sex == "girl":
     print("I love %S!"%name)
if sex == "man":
          print("Let's make love")

2

name = input("Name:")
sex  =input("Sex:")
age  = int( input("Age"))
if sex == "girl" :
     if age < 28 :
         print("I love %s" %name)
     else:
         print("姐弟恋很舒服!")
3

name = input("Name:")
sex  =input("Sex:")
age  = int( input("Age"))
if sex == "girl" :
     if age < 28 :
         print("I love %s" %name)
     else:
         print("姐弟恋很舒服!")
if sex == "man":
     print("我们来搞基!")

多分支

age = 25
user_guess  = int(input("you guess"))
if user_guess == age:
    print("恭喜,答对了")
elif user_guess < age:
     print("Try bigger!")
else:
    print("Try smaller")

练习

mark = int(input("please:") )
if mark < 39 :
     print("E")
elif mark<59 :
     print("D")
elif mark<79 :
     print("89")
elif mark < 89:
     print("B")
else:
     print("A")