if 条件：
满足条件后要执行的代码
else:
if条件不满足就执行这里
#_*_coding:utf-8_*_
---------------------------------------------------
#单分支
username = 'Lisa'
password = '123'
Username = input('Input your name: ')
Password = input('Input your password: ') if Username == username and Password == password :
print('Welcome to the system!')
else :
print('The username or password is not right!')
---------------------------------------------------
#双分支
Name = input('Input your name: ')
Sex = input('Input your sex: ')
Age = int(input('Input your age: ')) if Sex == 'girl' :
if Age < 18 :
print('She is a little princess!')
else :
print('She is going to marry!')
else :
print('No one likes him!')
---------------------------------------------------
#多分支
(1)
age = 26 user_guess = int(input('Input a number you guess: ')) if user_guess == age :
print('You are right!')
elif user_guess > age :
print('Try smaller!')
else :
print('Try bigger!') (2)#根据成绩不同，给予不同等级
Score = int(input('Input Score: ')) if Score <= 100 :
if Score >= 90 :
print('A')
elif Score >= 80 :
print('B')
elif Score >= 60 :
print('C')
elif Score >= 40 :
print('D')
elif Score >= 0 :
print('E')
else :
print('You are a fool!')
else :
print('Must be less than 100!')